230 



SCIENCE-GOSSIP. 



A Monograph of the Land and Fresh-water Mollusca 

 of the British Isles. By John W. Taylor, F.L.S., 

 with the assistance of W. D. Roebuck, F.L.S., 

 the late Chas. Ashford and other well-known 

 conchologists. Part L, 64 pp. Royal 8vo, coloured 

 plate and 138 figures. (Leeds : Taylor Brothers, 

 Sovereign Street, 1894.) Price 6s., or by sub- 

 scription 5s., per post. 



The first part of this long-expected work is at 

 last before us, and we may candidly say it exceeds 

 our expectations. Well considered, well arranged, 

 well illustrated and well produced, Part I. creates 

 the impression that we have at last in view a 

 standard work on this popular group of easily- 

 studied animals. It bids fair to be, for a long time 

 to come, much the best and most complete book on 

 its subject. The illustrations are excellent, 

 especially the coloured plate, considering the 

 number of colours used. We are enabled, by 

 permission, to re-produce several of the drawings 

 from the body of the work, and think our readers 

 will agree in saying they are good. 



Part I. of this Monograph deals with Definition 

 of Conchology, which term Mr. Taylor evidently 

 prefers to the more modern one of Malachology, 

 when speaking of the study of mollusca as a 

 whole — History, Classification, Nomenclature, 

 Synonymy, and the Shell. We are not aware of 

 .any work on the British members of the group 

 which has so well treated this last division. By 

 the aid of the author's remarks and excellent figures, 

 the whole subject is made most simple. The forms 

 of the shells are not only explained in letterpress, 

 but well illustrated. For instance : 



" The Peristome or Peritreme is the margin 

 of the aperture, and may be distinctly continuous 

 and detached during the whole life of the animal, 

 as in Cyclostoma elegans (which is figured), or only 

 distinctly continuous and detached at maturity, as 

 in Helix lapicida (also figured), and in the Clausilice. 

 It may, however, have the continuity of its outline 

 and character broken by the penultimate whorl, 

 and is then termed ' interrupted ' ; this separation 

 is, however, only apparent, as the whorl is, in all 

 cases, a complete tube, the penultimate whorl not 



Fig. 70. — Univalve with Interrupted Peristome. Helix 

 nemoralis, L., Spurn Point, Yorkshire. Collected by Mr. W. 

 E. Clarke, F.L.S. 



forming the inner wall of the aperture, as has often 

 been stated, but merely the foundation or support 

 for the inner portion of the last-formed whorl, thus 

 enabling it to have the thinness and delicacy which 

 usually characterises it, and has caused its 

 existence to be overlooked and ignored. The left 



side, which is so often closely appressed and 

 adherent to the preceding whorl, is called the Inner 

 or Columellar Lip, and also the Labium. Pfeiffer 

 terms the portion of the aperture supported by the 

 penultimate volution the Perietal Wall." 



Writing of the Gastropoda, which include all 

 our univalve shells, Mr. Taylor says : 



" The shell, with few exceptions, is composed of 

 one single piece or valve, hence the term univalve. 

 . . . The shell is usually of a conically tubular 

 form, enrolled, more or less closely around a 

 central axis, thus diminishing the space occupied 

 and securing a more portable and compact shell, 

 and is, with few exceptions, coiled dextrally — that 

 is, from left to right. It is in most species quite 



Fig. 1 



Fig. 19. 



Fig. 18. — A Dextral Univalve, Helix nemoralis L., Pipers- 

 town, Co. Louth. Collected by Miss S. Smith. 



Fig. 19. — A Sinistral Univalve, Helix nemoralis m., sinis- 

 trorsum, Fer., Sandhills, Bundoran, Co. Donegal. From Miss 

 F. M. Hele. 



easy to distinguish a dextral from a sinistral shell. 

 A simple method is to hold the shell with its apex 

 upwards and its mouth directed towards you, 

 when, if the aperture is on your right hand, the 

 shell is dextral, if on your left, sinistral, as shown 

 in the foregoing figures." 



Again, in describing the whorl ; 



" A whorl is one complete spiral coil, or volution 

 of the shell, and one completing the shell and 

 ending at the aperture is termed the body-whorl 



Fig. 36.— Female. Fig 37— Male. 



Cyclostoma elegans, Mull, Yarmouth, Isle of Wight, showing 

 the sexual difference in the tumidity of the whorls. Animals 

 dissected and the sexes verified by Mr. Chas. Ashford. 



This is usually, but not invariably, the_ most 

 capacious as well as the least formed, and in the 

 disecious species, as Cyclostoma elegans, is more 

 tumid and voluminous in female than in male 

 individuals." 



Fig. 83. Fig. 84. 



"Fig. 83. — Example: himncea pevegra, var. labiosa, Jeffr., 

 Greenhead Park, Huddersfield. Collected by Mr. J. 

 Whitwham." 



" Fig. 84. — Example : Limncea aaricularia, var. gibbosa, 

 Taylor. Pond, Moortown, near Leeds." 



In like manner, when describing terms such as 



