THIRD, OB \ i:i;MH l.i:\\ BRANCH I 16 



form of ili<" whorl until aK«»ut the sixth whorl. During tins volution 1 1 1 « - 

 abdominal region is raised t<> ;i slightly greater prominence, and the siphonal 

 ridge app< 



A I men from Semur shows pile, which are obtuse, but prominent 



and hint forward. These characteristics belong to the adull Btage, and arc 

 rved without change throughout the tenth whorl, tin the ninth and tenth 

 volutions the pile are very numerous, being respectively fort) one ami thirty- 

 eight in number, and the young of tin- -hell must Imve had a larger Dumber 

 of pilae than anv specimens described above. <m the second and third quarters 

 of tin- eleventh volution the pilsa became more and nunc depressed and finally 

 disappeared. The twelfth whorl was rounded and smooth, like that of the young, 

 and then: ition of the nostologic Btage. 



There is not usually much variation in the sutures of thi> species, 

 abdominal onsidernbly longer than the superior lateral lobes, and the 



inferior lateral- niav he of about the same length, or not more than half as 

 The superior lateral lobes are broad at the Bummits and serrated, the 

 inferior lati verj small in Mime specimens, owing to the -mall size 



of the first auxiliary saddles. The two larger -addle- may be of equal depth, 

 or the inferior lateral- somewhat the deeper; the superior laterals are, however, 



•mad in proportion to their depth, and the interior lateral- much narrower, 



• 1 1 . 1 1 1 \ ••\eii club-shaped. These proportions are apparent at an early 

 ind were observed np«>n the latter part of the third whorl before the 

 lopment of the marginal lob 



V»i:. B. 



rial) i ' >.--.». 



1 ■ '• .it ]. 1 -. pi Xii 



A mm. • 

 T»r 

 A mm t ■ 10-12 



K— 14 (pi. I \ 



I 



The true | . i I .- 1 • begin upon the thud whorl. There are about forty on the 

 third and fourth whorls, dec: i twenty live on the fifth whorl, 



and mi tie- seventh whorl there arc only about twentj pilm, the last of which 

 alread i exhibit symptoms of senile degradation On the eighth whorl 



tin- pihe an 1 to mere blunt folds The remainder of thi* whorl could 



not I- :. hut a fragment of the first quarter of the ninth show- that 



being merely lateral i idgee The 

 whorl at this time ha- an elevated abdomen, and tie- keel has disappeared. 



Th' '1 th.- preceding variety are to ; 



ill tie Opmenl of the pillD, and tie the adult -hell 



Tie- like tie ' 



hut mi the tilth volution tie- whorl -; I laterally, and t!. 



