304 JOURNAL OF CONCHOLOGY, VOL. 9, NO. IO, APRIL, igOO. 



exhibited to the Society to illustrate these remarks — the four absentees 

 being C. dalli Stearns, C. convolutus Sowb., C. prevosli Sowb., and 

 C. telatus Reeve. The last three of these are in our National Col- 

 lection, C. dalli being therefore the only form I have not been able 

 personally to examine. 



The border line between specific, sub-specific, and varietal forms 

 must necessarily be somewhat hazily defined, and may be considered 

 in certain cases somewhat arbitrary, but a long study of the several 

 forms convinces me : — 

 Firstly. — That there is a finality in the variability. 

 Secondly. — That the majority of the forms are, when once learnt, 

 comprehended without very severe difficulty, though, doubtless, 

 intermediates do occur, especially amongst the Tex/ilia Vera and 

 Abbales. 

 Thirdly. — That of the five characteristic and salient points, viz., form, 

 colour, size, texture, and disposition of marking, the variation in 

 one of these particulars alone does not count for much — one 

 needs a combination of two or three of them at least to produce a 

 deviation from the type sufficient to justify the creation of a 

 species. 

 But few of this group were known to or, at all events, differentiated 

 by Linnaeus, C. textile, the 'field of the cloth of gold' of old authors, 

 and C. aulicus, being the only two on which he imposed specific names. 

 The majority of the others have been described by Hwass, Kiener, 

 Mawe, Menke, the Sowerbys, and Reeve. 



The sub-genus Cylinder Montfort, 1810, may be thus briefly 



characterised : — 



Shell subconic, smooth, or very lightly striated, often somewhat solid, 

 spire more or less elevated, whorls never coronated, mostly numerous; 

 body whorl nearly always ventricose, excavate mostly at the suture, 

 aperture effuse, but rarely narrowed ; coloration white, with a more 

 or less complicated orange, brown, or grey reticulation, producing 

 a great variety of patterns in the several forms and species. 



Feeling it unnecessary to recapitulate the prefatory matter given in 

 my former paper, referred to above, as to geographical distribution, 

 affinities, etc., of Cylinder, and brief particulars as to the anatomy of 

 the genus Comes, I venture to propose the following arrangement of 

 the species and varietal forms of this section. It is a slight modifica- 

 tion only of that originally given, but tending, I believe, to a more 

 natural concatenation : — 



