Page:Encyclopædia Britannica, Ninth Edition, v. 19.djvu/538

Rh 518 P R P R PORBEAGLE, the name of a shark (Lamna comubica), mentioned in the works of older British authors as &quot; Beaumaris Shark.&quot; The short and stout form of its body contrasts strikingly with its much attenuated tail, which, however, is strengthened by a keel on each side and terminates in a large and powerful caudal fin. The snout is pointed, and the jaws are armed with strong lan ceolate teeth, each of which bears a small cusp on each side of the base (see fig.). The teeth are not adapted for cut ting, like the flat triangular teeth of man-eating sharks, but rather for seizing and holding the prey, which consists chiefly of various kinds of fishes and cephalopods. In the upper jaw there are from thirteen to sixteen teeth on each side, the third being remarkable for its small size ; in the Upper and lower tooth lower jaw from twelve to fourteen. The * Lamna. gill-openings are very wide. The porbeagle attains to a length of 10 or 12 feet, and is a pelagic fish, not rare in the North Atlantic and Mediterranean, and frequently wandering in pursuit of its prey to the British and more rarely to the American shores. The same species has been found in Japan and New Zealand, and perhaps also on the coast of California, so that the completion of the evidence as to its cosmopolitan range is merely a matter of time. Other closely- allied species (L. spaHanzanii, L. glaucd) are known to occur in the southern parts of the Atlantic, from the Mediterranean to the Cape of Good Hope. Very little is known of the mode of propagation of the por beagle, beyond the isolated statement by Pennant that two embryos were found in a female. No opportunity should be lost of making further observations on this point, and of preserving if possible the foetuses in their enveloping tunics. PORCELAIN. See POTTERY. PORCUPINE. This word, derived from the French pore-epic, or &quot; spiny pig,&quot; is applied to the members of the Hystricidse, a family of rodents whose most prominent peculiarity is their covering of long stout spines, which Porcupine. form a highly efficient protection against enemies, and which are better developed in this family than in any other mammal. Zoologically the porcupines are allied to the cavies, chinchillas, agoutis, &c., and with them form the great section Hystricomorpha or porcupine-like rodents (see MAMMALIA, vol. xv. p. 420). The Hystriddse are readily divisible into two sub families according to their geographical distribution, the Hyttricina or True Porcupines being confined to the Old World, and the Synetkerina to the New. The Hystricina are distinguished by their semi-rooted molars, imperfect collar-bones, cleft upper lips, rudimentary pollices, smooth soles, six mammae, and by many important cranial char acters. They range over the south of Europe, the whole of Africa, India, and the Malay Archipelago as far east wards as Borneo. They are all stout heavily-built animals, with blunt rounded heads, fleshy mobile snouts, and coats of thick cylindrical or flattened spines, which form the whole covering of their body, and are not intermingled with ordinary hairs. Their habits are strictly terrestrial. Of the three genera in this section, the first and best-known is Hystrix, characterized by its curiously inflated skull, in which the nasal chamber is often considerably larger than the brain-case, and by its short tail, tipped with numerous slender stalked open quills, which make a loud rattling noise whenever the animal moves. Its longest- known member is the Common Porcupine (//. cristata), which occurs throughout the south of Europe and North and West Africa, but is replaced in South Africa by //. africx- australis, and in India by the Hairy-nosed Porcupine (//. leucura), whose habits are described in the following notice extracted from Jerdon s Mammals of India. &quot; Hystrix leucura is found over a great part of India, from the lower ranges of the Himalayas to the extreme south, but does not occur in lower Bengal, where it is replaced by H. bcngalcnsis. It forms extensive burrows, often in societies, in the sides of hills, banks of rivers and nullahs, and very often in the bunds of tanks, and in old mud walls, &c. &c. In some parts of the country they are very destructive to various crops, potatoes, carrots, and other vegetables. They never issue forth till after dark, but now and then one will be found returning to his lair in daylight. Dogs take up the scent of the porcupine very keenly, and on the Xilghiris I have killed many by the aid of dogs, tracking them to their dens. They charge backwards at their foes, erecting their spines at the same time, and dogs generally get seriously injured by their strong spines, which are sometimes driven deeply into the assailant. The porcupine is not bad eating, the meat, which is white, tasting something between pork and veal.&quot; Besides the three large crested species of Hystrix above- mentioned, there are some four or five smaller species without nuchal crests occurring in north-east India and in the Malay region, from Nepal to Borneo. The second genus of Old -World porcupines is Atherura, the Brush- tailed Porcupines, much smaller animals than the last, with long tails tipped with bundles of peculiar flattened spines. Of the three species two are found in the Malay region and one in West Africa. Trichys, the last genus, contains but one Bornean species, T. lipura,, externally very like an Atherura, but differing from the members of that genus in many important cranial characteristics. The New -World porcupines, the Synetherina, have rooted molars, complete collar-bones, uncleft upper lips, tuberculated soles, no trace of a pollex, and four mammai only. Their spines are to a great extent mixed with long soft hairs ; they are less strictly nocturnal in their habits ; and, with one exception, they live entirely in trees, having in correspondence with this long and powerful prehensile tails. They consist of three genera, of which the first is formed by the common Canadian Porcupine (Erethizon dorsatus), a stout heavily-built animal, with long hairs almost or quite hiding its spines, four anterior and five posterior toes, and a short stumpy tail. It is a native of the greater part of Canada and the United States, where- ever there is any remnant of the original forest left. Syn- ct/ieres, the second genus, contains some eight or ten species, known as Tree Porcupines, and found throughout the tropical parts of South America, one of them extending northwards into Mexico. They are of a lighter build than the ground porcupines, are covered with short, close, many- coloured spines often mixed with hairs, and their tails are always prehensile. Their hind feet have only four toes, owing to the suppression of the hallux, but instead they have a peculiar fleshy pad on the inner side of the foot,