MUSEUM OF COMPARATIVE ZOOLOGY. 35 



scnts under a glass conspicuous calcareous prisms, radiating from the centre 

 of the shell. The muscular impressions are very variable in shape and 

 position as well as prominence. Ihe color is usually a livid reddish- 

 brown, with occasional white rays. The extreme nucleus of the shell is 

 mammillated. The lower valve varies in thickness according to the object 

 upon which it rests. If the latter be smooth and level, it is often very 

 thin and almost imperceptible, so that Miiller was not without justification 

 in overlooking it. The margin is usually rough or tuberculose, and the 

 muscular impressions vary as 'in the upper valve. 



The variety alba of Jeffreys is pure white, or occasionally with a few 

 radiating brown lines, but does not differ otherwise from the normal form. 

 From specimen figures and descriptions of C. turbinala, I have been 

 unable to discover any characters which are not common to varieties of 

 C. anomala. I agree with Mr. Jeffreys in thinking C. ringens Hoeninghaus, 

 to be synonymous with anomala on general considerations, but I have 

 seen no typical specimens of ringens. 



The few specimens of Crania dredged by the United States Coast 

 Survey Expedition (off the Sambos, Florida, in 116 fathoms, and off 

 the Sand Key in 105 fathoms) offer some apparently constant differ- 

 ences from C. anomala. They are somewhat distorted, very transverse, 

 and have pbscure indications of radiating i-ugosities. The shells are smaller 

 than C. anomala, have a strong concentric foliation caused by the imbri- 

 cation of the lines of growth. The color is much the same as in anomala ; 

 one white specimen with a few radiating brown lines was dredged on a 

 stone in 126 fathoms, off Sand Key, by M. de Pourtales. The interior of 

 the lower valves was of a green color. The posterior muscular impres- 

 sions are smaller and closer together than in C. anomala. It is very pos- 

 sibly, however, a strongly marked variety of that species ; but in case the 

 collection of a larger number of specimens should prove its distinctness, I 

 would propose for it the name of C. Pourtalesii. 



Note. — Not having personally been able to examine Poli's Test. Utriusq. 

 Sicilian, I have been indebted to the kindness of Mr. George W. Tryon, Jr., 

 for examining the work for me. It is evident to any one who appreciates 

 the binomial system of nomenclature, that Poli was in no sense binomial. 

 He named the animal generically and specifically, while the shell received 

 two additional names, making four in all, if we take them together, involv- 

 ing the absurdity of the animal being a different genus and species from 

 its shell. 



The references of Poli given below, from Mr. Tryon's notes, are as fol- 

 lows : — 



Vol. I, p. 34. " Genus 15, Criopus," description of animal as follows : 

 " Habitat in Anomia imperforata." 



