1890.] NATURAL SCIENCES OF PHILADELPHIA. 67 



begins at the apex and after traversing the first and second whorls 

 in an oblique direction, finally ends in the suture above the third 

 whorl. The top of the first whorl is flat ; the lateral out- 

 line of the whorls descends outwardly in a straight slant 

 to the carina, and from the carina to the suture below it 

 Pig J slants inward. The carina of the last whorl is much 

 lower, nearer the suture than that of the first, giving the two whorls 

 somewhat the appearance of a stumpy smoke-stack of a locomotive. 

 The last nuclear whorl ends with a triangular varix where (pre- 

 sumably) the shell began its growth after leaving the egg ; this varix 

 is thick, whitish and semitransparent ; from this point the shell con- 

 tinues to be nodulous until the spinose varices appear upon the 

 fourth whorl ; the suture between the first and second embryonic 

 whorls is very distinct. There are ten longitudinal ribs to each 

 whorl until the varices appear upon the fourth whorl. 



This species is separated from Mxirex oeca Sowb., by the top of 

 the first whorl being flat instead of round, as in the latter species. 

 The varix is triangular and well developed in scolopax, whilst in occa 

 it is rounded and not so well developed. It is separated from Murex 

 tribulus Linn., by the lateral outline of the second whorl being 

 straight instead of rounded as in the latter species. 



Murex occa, Sowb. (Fig. 2). 



The embryonic nucleus consists of two nearly white, smooth 

 whorls ; the first is a little rounded knob, and the second is distinctly 

 carinated and about twice as large as the first ; the carina commences 

 about midway of the first embryonic whorl and con- 

 tinues in an oblique direction until it finally disap- 

 pears in the suture above the third whorl ; the lat- 

 ei'al outline of the first whorl is rounded while that 

 ^'^' ^" of the second is carinated as in the first whorl of scolopax. 



The carina of the second whorl is about midway of the whorl. Look- 

 ing at the whorls from above they are seen to increase regularly, the 

 succeeding whorl being twice the size of the one before it. 



The last apical whorl ends with a small thread-like varix ; from 

 this varix the whorls are nodulous until the spinose varices appear 

 upon the fourth whorl ; there are nine ribs to each whorl until the 

 spinose varices appear ; the suture between the first and second em- 

 bryonic whorls is quite deep ; the apex is a little flattened or im- 

 mersed, and bent down on one side. 



