POT, BTH, OB I 0RO1 BBANl II. 165 



Vu. c 



The whorls are stouter than in variety B, and acquire on the firs! quarter 



<>f the fourth whorl, or later, a close resemblance to tl ltmn. The 



r lateral Baddli nsiderablj deeper than the Buperior laterals, the 



or lateral lobes considerably Bhorter than the superior laterals, and pointed. 



The sutures were observed upon i In- latter pari of the fifth whorl. 



SUBSERIES. 



Arniocoras seruicostatum, Htatt. 



I I. I || in I... low, Pi, Mil 



Am' - JOX, Vinin of Torki 51.' 



. pi. i Qg 7 ( no) ' 



... -71 



v\ 



Yak. A. 



II .1. Ill |g, Ml. 111. 



During the first four and three quarters <>r five volutions, the Bhell closelj 

 resembles \ tbile, var. acutidnrsale. After this the pihe appear. Tln-\ are 



at first broad and depressed, but possess the sharp definition <>i true pilae, and 

 terminate abruptly on the edge <»t the abdomen. The abdomen is rounded, and 



the keel a distinct though depressed ridge. It^ tin I' nppearai could n< >t be 



nined, but it was plainly apparent on the second <>r third quarter <>f the 

 fifth whorl, and previous to thi* the aspect of the abdomen was precisely that of 



Var. B. 



ii .1. mi,., ii ii. 



In tlii> variety the young resemble very closely the adults of I 



Tin- pilas make their appearance earlier than in variety A. but, 



while I oming more numerous, often retain their fold-like aspect, and terminate 



abruptly mar the abd en. The keel appears about the same time as the pilse, 



and may be either with nr without >li'_ r ht channels. In some specimens the 

 whorls become stouter than usual in the adult, and the genicuhe prominent. In 

 men they are inclined posteriorly. 



In the Museum of Stuttgnrdl there are three B| itnensofthis variety, one 



B i aii'l one from Muhlfingen N T o ih in the Qeometi i 



I'. icklnndi l>'-'l Another from Filder was found in 1 1 • « - Angulatus ! 



• Tl 



'i 



• ■ 



