110 THE NAUTILCS. 



fourth whorl has some obsolete longitudinal ribs and spiral lines at 

 the base ; thejifth, sixth and seventh have prominent longitudinal ribs 

 and spirals, without varices ; eiyhth with similar sculpture and one 

 varix ; on the ninth the ribs and spirals form slight nodules at the 

 shoulder, with one varix ; tenth subnodose with coarse spirals ; eleventh 

 subnodose with coarse spiral ridges and fine intermediate lines cover- 

 ing the entire whorl. Length 49 mm. 



Though larger, it is apparently the same age as the specimen of 

 the typical form. Whether the above characters will prove to be 

 constant I cannot say. The typical form seems to assume the larger 

 spines of the adult one whorl in advance of the variety alatus. The 

 variety nicaraguensis is smaller than either pugilis or alatus, and the 

 spiral ridges usually cover the entire body whorl of the adult shells. 

 S. gracilior loses its spirals much earlier than S. pugilis. 



In the adults there are some marked variations both in color and 

 form. The typical pugilis is less variable in color, ranging from an 

 orange-yellow to carnelian-rtd ; alatus varies from white to purple, 

 and from a purplish brown to deep orange or carnelian-red. Exter- 

 nally pugilis is usually a uniform yellowish brown, while alatus 

 varies from a light yellow to a dark brown, the latter color often dis- 

 posed in bands or zigzag markings; nicaraguensis is of a uniform 

 dark salmon color. 



The length and shape of the spines vary in both forms. A figure 

 in Chemnitz (Conch. Cabinet, X, tab. 196, f. 1493), shows the rows 

 of spines at the periphery ; the two united would give the broad, ver- 

 tically compressed spines as figured by Clienu (Manuel Conch., I, 

 p. 225, fig. 1582). In the many specimens which I have examined 

 I have never seen these forms ; they probably represent unique ab- 

 normal specimens. Tryon is wrong in making the non-spinose form 

 of alatus typical. The figure referred to by Gmelin (Conch. Cab- 

 inet, III, tab. 91, f. 894) is the common brown form of Florida, with 

 a row of subacute tubercles on the body whorl. Lamarck, under S. 

 pyrulatus, refers to the same figure. Specimens of alatus, in which 

 the tuberculate spines are entirely wanting, are not common, only 

 about five or ten per cent. I found the greatest number at Marco, 

 Florida. A spineless form of pugilis has also been recorded. A 

 specimen in the Boston Society's collection has the spines wanting in 

 the greater portion of the body whorl, as figured by Knorr, III, tab. 

 16, fig. 1. 



