﻿RHYNCHONELLA. 



103 



am not therefore surprised that palaeontologists should have felt embarrassed, and 

 have identified with the imperfect illustration shells of an entirely different character. 

 Having obtained the loan of the original example, through the kindness of its possessor, 

 Mr. J. de C. Sowerby, I have been able to study and illustrate its characters with sufficient 

 care. It is always very hazardous to establish species from the inspection of a single 

 specimen, and especially among so variable a group of shells as that of the Bhynchonella. 

 Sowerby's T. Mantice appears to me to be nothing more than an accidentally elongated 

 malformation of B. pleurodon, wherein the mesial fold (composed of five ribs) had become 

 unsymmetrical, from being twisted more to one side than to the other, an occurrence not 

 uncommon to many species of Bhnychonella, which in their normal state have the fold and 

 sinus in the middle. I purposely avoided referring, in the list of references, to the works 

 of those authors who have alluded to T. Mantice, as they were evidently unacquainted with 

 the characters of Sowerby's shell, which measures nine lines in length, eight in width, and 

 six in depth. Notwithstanding the priority of date of B. Mantice over B. pleurodon, I 

 believe all palaeontologists will prefer retaining Phillips's denomination for the species ; 

 especially so as Sowerby's one has unfortunately been the cause of so much misapprehension, 

 being founded on a malformation. At page 146 of the first volume of D'Orbigny's 

 ' Prodrome,' T. proava of Phillips is considered a synonym of T. Mantice, but I believe 

 the French author's guess to be incorrect. 



In 1843, Professor De Koninck described and figured a totally different shell under 

 the name of T. Mantice, and to which he had likewise added T. radialis of Phillips, as 

 synonym, but the distinguished Belgian author has since then recognised his mistake. At 

 page 437 of M'Coy's work on ' British Palaeozoic Fossils,' a shell is described under the 

 generic and specific appellation of Spirigerina (?) Mantice, Sow., sp., but as no illustration 

 is appended, all that can be said is, that the shell so described cannot have belonged to 

 Sowerby's species, because T. Mantice possesses all the exterior appearances and characters 

 of a true Bhynchonella, and none of those of a Spirigerina, nor does it present " a large, 

 high, flat, cardinal area," or any appearance of the punctured shell-tissue, described in the 

 work above quoted. It is, therefore, certain that Professor M'Coy must have had some 

 other species before him while drawing up his description. 



Secondly. — Bhynchonella (Ter.) venlilabrum, Phillips (pi. xxiii, figs. 13, 14), ( £ Geology of 

 Yorkshire/ vol. ii, p. 223, pi. xii, figs. 30, 38, 39, 1836). 



Professor Phillips states that he " is not certain whether his species be distinct from 

 T. sulcirostris, that it has no mesial elevation, the ribs rounded, and vanishing towards the 

 margin.'' In PI. XXIII, I have reproduced the author's figures, but feel but little 

 doubt while placing B. ventilabrum among the variations of form, or synonyms of B. 

 pleurodon, for the typical example (fig. 13) exactly resembles certain specimens of the 

 last-named species, in which the mesial fold is indistinctly marked ; in fig. 14 it may, 

 however, be clearly perceived. B. sulcirostris has been with some doubt considered a 

 synonym of B. pugnus, from the shortness of its lateral ribs, and I regret not having been 



