SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 59 



PIvATE V. 



Figs. I and 2. Branchia or gill. Section* of gill magnified, 

 showing filaments or tentacular junctions. 



Figs. 6 and 7. Views of filaments and tentacular junctions, 

 more highly magnified than figures i and 2. 



Figs. 3, 4 and 5. Ocelli and tentacles of the mantle-border. 

 Figs. 3 and 5 show the relation of eyes or ocelli to the tentacles, 

 the first named, figure 3, slightly enlarged. Fig. 4 has tentacles 

 alone, also enlarged. 



Fig. 8. Showing the gill membrane around part of the ad- 

 ductor muscle: g, generative organ; k, kidney; g. m., gill mem- 

 brane; br, branchia or gill; a, anal aperture; r, rectum; h, heart. 



Fig. 9. Another view of the heart, auricles and ventricles, 

 with the intestine passing through. 



Fig. 10. A second view of the gill-membrane, somewhat en- 

 larged, detached from the adductor muscle and spread out, also 

 part of the gill: p. m., point of the membrane that at all times is 

 free frotn the adductor muscle. 



♦Excepting the gill sections, the drawings, for the most part, were made natural size. 

 As they were made from several specimens, some alcoholic, they represent an idealized. 

 Pecten. 



Thanks are due Miss Alice Cooperfor her accurate reproduction of the author's sketches 

 The shell, figs. 1 and 2, plate IV, was drawn from the original by Miss Cooper. 



The author is indepted to Prof. C. A. Whiting, for photographic reproductions of cross 

 sections, and also for a drawing of the same. 



