Page:Nature (IA natureinternati04lockgoog).pdf/297

Rh THURSDAY, FEBRUARY 10, 1876

OLD AND NEW WORLD SPIDERS

Descriptions of Several European and North-African Spiders. By T. Thorell. Kongl. Svenska Vetenskaps. Akademiens Handlingar, Bandet 13, n.0, §, pp. 1203. (Stockholm : Norstedt and Séner, 1875.)

Al Collection of the Arachnological Writings of Nicolas Marcellus Hents, M.D. Edited by Edward Burgess. ‘With Notes and Descriptions by James H. Emerton. Forming No. II. of Occasional Papers of the Boston So- ciety of Natural History, pp. 1—171, Pl, 1—21, (Boston: U.S.A, 1875.) ‘ T is a somewhat singular coincidence that the two

works at the head of this article should have been published just about the same time, We shall eadeavour briefly to show the value and bearing of cach.

It is probably undeniable that an illustrated book on

any branch of natural history is more acceptable to the public—certainly more attractive—than one wholly devoid of pictorial illustrations ; and not without good reason, for it is well known what great assistance even the advanced student obtains from a single glance at an illustration, when traced by a hand well cognisant of the point sought to be illustrated, even though the hand may be entirely wanting in artistic power. The want, however, of drawings to assist the comprehension of the dry details of natural objects may be reduced to a minimum by the presence of good diagnoses. Pleasant are those pages where both these helps exist ; dreary and uninviting indeed (thaugh sometimes inevitable) are long and dry details of form, structure, and colour, when unenlivened either by drawings or diagnoses. From such dreariness Dr. Tho- rell's two hundred quarto pages of descriptions of spiders (under the title given at the head of this notice) are saved by the excellent diagnosis with which each descrip- tion is preceded. It not uafrequently happens that a diagnosis is a mere formal abstract of the longer descrip- tion that succeeds it ; this is, however, not the case in the present instance, where each diagnosis puts before us just such distinctive points of special form, structure, and colour as the describer, were he at all able with his pencil, would endeavour to delineate by means of rapid sketches and dissectional drawings,

Tn respect to this point Dr, Thorell remarks (p. 4), that he has “ prefaced his descriptions with diagnoses, although this is not done by the generality of modern arachnolo- gists,” it is, he says, “my firm conviction that tolerably good diagnoses very greatly facilitate the determination of unknown speoies, even though they be not real [by the term read Dr. Thorell appears to mean /i//] definitions.” This places a diagnosis, in relation to the full description, exactly on a par with the part delineation and dissectiona] drawing when compared with a full artistic illustration ; neither the diagnosis nor the dissectional drawing, how- ever characteristic, precludes the necessity for a full uescription, por for a full artistic illustration where it can be had ; in fact, were it not a serious question of space

and cost, amounting often to a positive bar, no natural |

object could be said to be well and properly described and illustrated without @ diagnosts, such as that mentioned Von. xi1,—No. 328

above, @ full description embracing an almost photo- graphic accuracy of every part, and (where closely allied forms exist) « differential description as well, besides full, and dissectional drawings. Of course the full description would be broken up into ordinal, family, generic, and specific characters, each in their proper place ; the three first only requiring repetition where, in the individual examples, they happened to depart from the strict type.

The introductory pages of the work before us are in English, while the descriptions are in Latin; and the materials from which Dr, Thorell has drawn them up have been gathered from various collectors and widely distant parts of Europe, including the northern shores of Africa; which last, under the term “ Mediterranean Basin,” Dr. Thorell rightly joins to Europe as a single zoological province. 202 species, belonging to 51 genera, distributed among 12 families, are described, 24 of the species being given as new to science ; a large proportion of the remainder, together with four new genera, having been published as new but a short time before, under the title “ Diagnoses Aranearum Europzarum aliquot Novarum Scripsit.” T, Thoretl, in Tijds. voor Entom. Deel xviii, 875,

Dr. Thorell states (p. 1) that he follows here, with some slight modifications, the classification proposed in his former work “ On European Spiders ;” this mention gives tise to a long foot-note, of two closely-printed pages, in which he examines and criticises M. Eugéne Simon's strictures of his system (published in “Aran. Nouv. ou peu Conaus du Midi de Europe,” 2° Mém. ; “ Mdm. Soc, Roy. de Sciences de Liége,” 2° ser. t. v., 1873). It is not necessary to enter here into the merits of this little pas- sage of arms, but we come to the conclusion, on perusing it, that Dr. Thorell is probably right in saying that he “has not been so fortunate as to make himself under- stood” by M. Simon. At page 7, the latter author’s theory respecting the eyes of spiders is discussed in another long foot-note. This theory has already been noticed in these columns (vol. xi, p. 224). Dr. Thorell, while entering fully into the question of the real nature and structure of the eyes of spiders, says, with regard to this theory, that “it is to be wished that M. Simon would somewhat more accurately describe the researches on which his views are founded ; his theory is, in fact, so much the more remarkable, as no previous naturalist who has investigated the finer structure of the eyes of spiders, appears to have been aware of the ex- istence of any distinction between day-eyes and night- eyes.” Independently, however, of M. Simon’s theory, the question as to the nature of spiders’ eyes is a very interesting one ; and very valuable would be those re- searches which should reveal ta us the actual anatomical condition of such eyes as, for instance, the apparently atrophied, and probably useless, ones of the hind-central pair in the genus Qecobius, Luc.

A footnote of considerable length is appended to pages 66 and 67 on the venom of various species of the genus Lathrodectus, comparing it with the reputed venom of Gateodes arancotdes, and questioning the correctness of ‘M. Simon’s conclusions (Mém. Soc. Roy., Liége, 2 ser. tv), that the bite of Lathrodectus 13-guttatus is not poisonous. Another point, also of great interest, is noted at p. 65, where Dr. Thorell speaks of traces of segmenta-

q �