74 J?ir0t annual Ucport 



Thais ostrina Gld. 



While dead shells are fairly common between tides, living speci- 

 mens appear to be rare here. 



Astyris hindsii Roe 

 Fairly common on sea-weeds between tides. 



Amphissa versicolor Uall. 

 Empty shells of this only, were encountered. 



Macron lividus A. Ads. 

 Common attached to fucus. 



Volvarina varia Sby. 

 Between tides, but not common. 



Olivella pedroana Conr. 

 A few dead shells found. 



Conus californicus Con. 

 Common, attached to fucus. 



OP1STHOBRANCHIATA 



TECTIBRANCHIATA 



Aplysia californica Cooper 



(Figure 37) 



These enormous purplish sea-slugs were occasionally encountered 

 in the lower tide-pools. A good many specimens were dissected. 



NUDIBRANCHIATA 



Numerous species of remarkably beautiful nudibrauchiate mol- 

 lusks are to be found at Laguna Beach, and they are among the most 

 attractive objects of the tide-pools, never failing to call forth the 

 most enthusiastic exclamations from both students and visitors. 

 "Exquisite" is the only word that adequately described them. I 

 determined the species so far as I could from MacFarlaud 's writings, 

 but a large part of the species seem to be underscribed. In the works 

 of Bergh and other writers on this group, our west coast species 

 seem never to have been treated. 



Chromodoris porterae Cockerell 



(Figure 39 B) 



Color prussian blue, the dorsum of a deeper shade than the sides. 

 Mantle narrowly white edged. On the dorsum is a median line of 

 light blue running from between the rhinophores to the branchiae. 

 On each side, half way between this line aud the mantle edge, a broad 



