FOURTH, OB l !;\N BH INCH 177 



prominent I'poti either the latter pari of the fourth, or first quarter <>i' 

 the fifth volution, the whorl attained its adull 



Dm _ • • first volution the increase laterally bad been verj great, forming 



p umbiUcuc lently the tubercles and added to the width 



of the abdomen <>t' the earlier whorls, giving a general resemblan I latum. 



The young whorls «>; specimens in which tb on the 



tli t m1 wh.nl were usually rounder, and exhibited, when seen from the side, onh a 



v.t\ semblance to Cor. latum. These passed suddenly, so fast <liil the 



folds and then true pilae, into the stage in which they re- 



■embled i Ifter this stage, the preponderance of the abdominal 



- i marked, though it may be maintained thi the fourth 



Quensl imen, with a living chamber one volution in 



length, 1 exhibited a broad abdomen on the fourth whorl. 



The genicular are a1 first not tuberculated, bul sharp and angular, as in some 

 The abdomen, how< not usually become suffi- 



ciently prominent in the carl owth to bear comparison with thai 



liter this ] -I the umbilical Bhoulders are developed nunc 

 irtionally, and finally on the fifth volution the whorl becomes broader <l<n- 

 sally than near the abdomen. The dorsal curves of the pilae become more 

 prominent, and sink or are contracted to form the tubercul la?. These 



quently bend forward '" some specimens, ascending the abdomen. This 

 lay <>.-,-m i the third whorl, >>v. <>u the other hand, lie 



omitted altogether, even in adults. 



This description <>l the development may be curiously altered bj a 



malformation of the abdomen. The pilae, Plate III. Fig. 7. 11,* are continued 

 idomen iu ol waves entirely obliterating the 



k«-«l and channels. 



Th • young which differ considerably from one another in the 



ii. some being !\ broad and flat during 



the young who chilly the microceran forms, have much nar- 



The number <>f the pike ah these parts being more 



■ I in the broad, fiat voting than in othi 



In th<- i if adult specimens, the superior lateral Baddies are deeply 



divided by two lobes, and sprend out laterally beyond, or on t! 



uen, however, from Seinur, though not differing in other 



ddles bo l"ii_r and narrow that the superior I 

 nicular line. The abdominal lobe extends beyond the 

 rior I ■ ■ i one third, and th< 



■ 



B 



is, w hii li 

 i the iin ' late 



