196 MAZATLAN UNIVALVES 
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 surface, asin L. sanguineus. Long. ‘17, lat. °12, alt. 03. 
Hab.— Mazatlan ; off Spondylus ealcifer, extremely rare ; 
LP’pool Col. 
Tablet 902 contains the sp. and 2 odd valves. 
254, 6. LEPIDOPLEURUS BULLATUS, var. CALCIFERUS. 
L. ? bullatus, areis lateralibus ‘tuberculatis, sine bullis, lined 
diagonali quasi calculis instructa ; areis centralibus lineis tuber- 
cularum trregularibus, tuberculis minoribus ; pilulis pallir 
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, 7. s. 
2D. t. “Lophyro striato-squamoso” valvis et limbo pallii fere 
omnino simulante, sed marginibus valvarum acutis, haud serratis. 
A smashed specimen in fresh condition was found on a 
Spondylus, not distinguishable externally from Lophyrus 
striato-squamosus, 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. Nuttall, Esq., 
I was fortunate enough to discover between two lamine 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, 
