Page:VCH Cornwall 1.djvu/326

 A HISTORY OF CORNWALL segments with four carinae. The eyes and first antennae in this family are borne on movable segments. The rostrum is articulated. The principal branchiae are attached to the pleopods. Before leaving the stalk-eyed Malacostraca the reader will no doubt welcome a quotation from Jonathan Couch's History of the Fishes of the British Islands?- in which a discussion of the cod's voracity includes an interesting contribution to our present subject. After mentioning several strange miscellanea of its diet Couch continues : ' In one instance six Picked Dogfishes, each 9 in. in length, were found in the stomach of a cod ; and the following list of crustacean animals (crab and lobster kinds) in the stomach of these fishes, which were taken in the west portion of the British Channel, will show the strong preference which the cod manifests for that sort of food, of which also, we may add, their digestion is so powerful and speedy, that, in a short time after being swallowed, the hard and brittle crust of the crabs is made so soft by the action of the gastric juice, that their legs may be twisted round the finger. ' Crabs. Stenorynchus phalangium, Achaeus Cranchii, Inachus Dorsettensis, I. dorynchus, I. leptochirus, Hyas coarctatus, Eurynome aspera, Xantho tuberculata, Cancer pagurus, Portunus corrugatus, P. arcuatus, P. marmoreus, P. pusillus, P. longipes, Gonoplax angulatus, Atelecyclus heterodon, Corystes cassivelaunus, Pagurus Bernhardus. ' Long-tailed Crustaceans, lobster kind. Galathea squamifera, G. strigosa, G. dispersa, G. Andrewsii, Munida Rondeletii, Gebia stellata, G. deltura, Nika edulis, N. Couchii, Squilla Desmarestii, Alpheus ruber, Scyllarus arctus. ' In this enumeration the notes of Mr. W. Laughrin, A.L.S., are united with my own ; and of these species the Scyllarus arctus offered only one example, which is now deposited in the British Museum ; but of the Munida Rondeletii, which is usually considered as not a common species, "there have been found not only numerous specimens, but these have often been of remarkable size. The longest leg of an example described by Mr. Bell in his beautiful Natural History of this tribe measured 6 in., but I have found the same part to measure 9 in., with the antennae of the same length as the leg.' Under the alternative names of Gadus morrhua and Morrhua vulgaris, the cod has been shown also by Mr. Cocks to have a thoroughly carcinophilous palate, which it shares with the haddock, the piper, the tubfish and many other gourmands. The transition to the sessile-eyed Malacostraca is not abrupt, since there is a small peculiar group in which the eyes are sessile, but the affinities are nearer to the Podophthalma. To this order, for some time known as the Cumacea, the name Sympoda has lately been applied. 2 Hitherto only two species appear to have been noted from Cornish waters, though many more will certainly be found therein when sought for with moderate diligence. Of Diastylis rathkii (Kr6yer) Bate says ' It was first taken in Cornwall, at St. Ives, by the late Mr. Barlee. From Falmouth I received it from Mr. Webster." He reports his own species Eudorella truncatula (Bate) from Plymouth Sound. 3 In the former genus there is a very distinct telson, in the latter there is none. The other sessile-eyed orders, Isopoda and Amphipoda, though disregarded in Couch's Cornish Fauna, not much later were collected with some diligence by Cocks, and in due course attracted the notice of Couch and his son, and eventually, through the well-known work of Bate and Westwood, to which Norman and others lent powerful assistance, they began to assume an important place in the natural history of Great Britain. The economic value of little crustaceans is perhaps seldom appreciated. Out of the multitude of aquatic animals we only use a few species for food, and as a rule trouble ourselves little to consider how those animals themselves are nourished. But, if, as above noticed, large fishes eat the larger crustaceans, small fishes eat the smaller, and just as the strong mammals prey upon the weaker, so are the jaws of one shrimp nicely adapted for masticating another. By a circuituous route the microscopic organisms of this class almost undoubtedly render to mankind such services as our noblest philanthropists cannot hope to emulate. The genuine Isopoda, like the Squillidae, have the breathing organs in the pleon, but there is a tribe of anomalous Isopods which have their respiratory arrangement in the front or cephalo-thoracic part of the structure. This tribe is sometimes called Tanaidacea, sometimes Chelifera. It comprises two families, the Tanaidae and Apseudidae. In these the heart is placed near the head, as in the Amphipoda, instead of near the tail, as in other Isopoda. The first legs are chelipeds, as in crabs and lobsters, but here there are seven pairs of trunk-legs instead of five, so that the first pair correspond not with the chelipeds of a crab but with its second maxillipeds. Of the Tanaidae, Bate and Westwood describe Tanais vittatus (Rathke) and T. dulongli (Audouin) from Polperro, and Paratanais fonipatus (Lilljeborg) 4 from Plymouth Sound. Although the English 1 Op. cit. (1864), vol. iii, 55. Art. Malacostraca. 3 ' Revision,' pp. 41, 42. 4 British Sen. Crust, vol. ii, pp. 125, 129, 138. 274
 * Stebbing, in Willey's Zoological Results (1900, part v, p. 606), and Encyclopaedia Britannica Suppl. (1902),