OF CONCHOLOGY. 261 



obtained more than a hundred specimens on the rocks, between 

 tides, at Monterey, California, in the month of January, 1866. 

 At this time they were well filled with ova, and all the speci- 

 mens obtained contained ova; not a single male came to hand. 



The foot is oval, thin, dull waxen below ; sides of foot smooth, 

 black, the extreme edge pellucid white or yellowish ; the whole 

 nearly as long as the shell. Mantle thin, extending little be- 

 yond the foot on the sides, but some distance beyond the head 

 in front ; edge thickened, smooth, whitish, with a crowded row 

 of fine blackish papillae on the extreme edge ; another of larger 

 and more distant papillae inside ; and lastly a row of still larger 

 ones inside of the last, placed opposite the spaces between 

 the papillae of the second row, and somewhat further apart. 

 The branchial lamellae exactly resemble those of Patella vul- 

 gata, as described by Dr. Williams, but are somewhat less crowded 

 and of a pellucid wax color. They are equal on the sides and 

 behind, but diminish in size on each side of the head, and are 

 interrupted in front for a space as wide as the head. The 

 gill is elongate-triangular, quite large, attached by both edges 

 for a short distance to the mantle above it, forming a shallow 

 bag-shaped cavity ; it is curved a little to the right and is in- 

 serted to the left of the neck, in the commissure between the 

 neck and the mantle. In structure it is a flat plate, with 

 rounded, striated edges, bounded by an impressed line, which 

 is stronger on the under side. Inside of this line, above and 

 below, extend a series of equal tranverse laminae, less strongly 

 marked toward the apex of the gill, which is smooth and pro- 

 duced at the tip. A nerve and blood-vessel pass along the 

 left edge of the gill ; the laminae are hollow and profusely 

 furnished with blood-vessels. The hood above the gill is also 

 extremely vascular. 



On the right side of the neck is a smooth subcylindrical 

 anal papilla, obliquely truncate, so that the foramen opens 

 toward the right side of the animal. From the foramen project 

 forty or fifty long, slender, cylindrical, white papillae or tenta- 

 culate processes, but they originate inside of the edge of the 

 aperture, which is entire and closed by a subspherical process of 

 the integument. The renal organ opens to the left, outside of 

 this papilla, through a very minute non-elevated orifice, in which 

 It differs from. Patella vulgata. To the right of the anal papilla 

 is a rounded tubercle, with a semilunar orifice. There are no 

 other papillae or tubercles in the vicinity, nor could any "capito- 

 pedal orifices" be detected as described in Patella by Lankester. 

 The head and tentacles are whitish below and black above, but 

 the black color does not extend behind a line drawn from the 



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