54 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 



lops makes a spring in the water. When the shell is opened by 

 the little animal the body appears to be of a bright orange yellow 

 color. In each open valve of this headless moUusk one can see 

 the mantle border fringed in gay colors and also a row of bright, 

 black ocelli (eyes) that with the gay color of the body* of the 

 shell fish forms a picture never to be forgotten. When uncov- 

 ered with water pectens outline their shell in the sand where 

 mounds of it reveal their rounded form. 



ANIMAL. 



Mantle: Filmy, white, showing very plainly the scalloped 

 impression of the ribs of the shell. Above this scalloped im- 

 pression the mantle is very thin and transparent. (Fig. 4, plate 11) 



The mantle is open entirely on the byssal side and ventral 

 edge but is closed near the adductor muscle, just below the post- 

 erior auricle or ear of the shell. The mantle is open at the mar- 

 gin of both auricles. Is closed along the dorsal edge of the shell, 

 that is, below the hinge line. (Why is the mantle open under 

 each auricle of the shell? Is it for the entrance and exit of water? 

 I have not satisfactorily found an answer to this question.) 



The mantle has a double border, one that has been referred to 

 as white, bearing the impress of the ribs of the shell, and, the 

 other close to the ventral margin of the pecten, which shows the 

 ocelli and rows of points or tentacles lying closely together. (Figs. 

 3 and 5, plate V). These form a heavy fringed border. This 

 border is yellowish alternating with black caused by the tentacles 

 of the mantle border being a yellowish or dirty white color with 

 black lines covering the base of these fringes. Short nodules, 

 also with fine stripes of black fill in the interstices between the 

 numerous ocelli. These ocelli are situated on nodules or short 

 tentacles that are somewhat rounded, not sharp pointed like the 

 tentacles without the ocelli or e^'-es. The ocelli are bright green 

 with red centers which I may, for convenience, call the pupil. 

 (Fig. 3, page V.) Besides the green color of the iris (?) there is 

 present a purple color giving the eyes an irridescent effect. This 

 is in some lights, in others the ocelli have a bluish tint and each 

 center or pupil is opaque or a dull white color. These eyes do 

 not extend the length of the mantle border. Besides the well 

 developed ocelli there are always present a number, sometimes 



♦While the yellow part visible appears to be the body or visceral mass, it is in fact one 

 or more organs of that body. 



