196 MAZATLAN UXIVALVES 



diagonal towards the jugum ; and the granules over the whole 

 surface, somewhat corrugated on the jugum. The internal 

 plates of all the valves have an external projection from the 

 outer siirface, as in L. sanguineus. Long. '17, lot. '12, alt. '03. 

 Hob. Mazatlan ; off Spondylus calcifer, extremely rare : 

 L'pool Col. 



Tablet 902 contains the sp. and 2 odd valves. 



254, b. LEPIDOPLEURUS BULLATUS, var. CALCIFEEUS. 



L. ? bulletins, areis lateralibus ' tuber culatis, sine bullis, lined 

 diagonals quasi calculis instructd ; areis centralibus lineis tuber- 

 cularum irregularibus, tuberculis minoribus ; pilulis pallii 

 majoribus, confertissimis. 



Tablet 903 contains one specimen which presents the above 

 differences. Whether they be specific, cannot be determined 

 without other and older specimens. 

 Hab. Mazatlan ; 1 sp. off Spondylus ; L'pool Col. 



255. ? LEPIDOPLEURUS MAC-ANDREI, n. s. 



? L. t. "Lopkyro striato-sqiiamoso" valvis et limbo pallii fere 

 omnino simulante, sedmarginibus valvarum acutis, kaudserratis. 



A smashed specimen in fresh condition was found on a 

 Spondylus, not distinguishable externally from Lophyrus 

 striato-sguamosus, but unexpectedly presenting the sharp in- 

 sertion-plates of Lepidopleurus, at the same time that the scales 

 agreed exactly in the remarkable character of the former 

 species. Not daring to build on such imperfect data, I sus- 

 pended my judment : but when examining some specimens of 

 Margaritiphora Mazatlanica in the collection of T.lN"uttall,Esq., 

 I was fortunate enough to discover between two laminae a per- 

 fect little Chiton, which on examination turned out to be exactly 

 identical with the smashed specimen from the Spondylus. 

 Having loosened a terminal valve, and subjected it to repeated 

 examinations under a half-inch achromatic, I am unable to dis- 

 cover any trace of serration,* while in L. striato-squamosus it 

 is unmistakably evident. In the absence of further evidence, 

 we are obliged to conclude, either (1) that the same species 



* In examining young Chitons, it is necessary to guard against being misled 

 by the gill-like lamina, which, passing over the insertion -plates, is apt to give 

 them (under a low magnifier) a serrated appearance. 



