1918 Bovard and Osterud; on Embryological Material 133 



ment does not proceed normally in sea-water. Specimens brought to the 

 laboratory have laid eggs on the side of live-boxes out of doors, but none 

 have given normal results in the laboratory aquaria. The early stages 

 are easily followed, but later stages necessitate stained mounts. The veliger 

 stage is passed in the shell. 



Acmaea pelta Eschscholtz, and Acmaea patina Eschscholtz. These 

 two limpets are very abundant on the rocks between tide levels. The 

 ovaries are crowded with large angular eggs with large germinal vesicle 

 and distinct chorion; so are evidently approaching maturity (July 1917). 



Crepidula adunca Sowerby. Occasional animals associated always 

 with other shells. They are found in shallow water in trawling and along 

 rocky shores. The eggs are very large and filled with a yellow yolk which 

 makes the eggs quite opaque. Six to eight eggs are laid in a single bal- 

 loon-shaped capsule, and several capsules attached in a small bunch. The 

 eggs are laid early in July (1918). 



Cryptochiton stelleri Middendorf. Common on reefs at extreme low 

 tides, and in trawling in shallow water. They had passed their season be- 

 fore the last of June in 1917, and by July 15 in 1918. 



Katherina tunicata Sowerby. Abundant forms easily collected along 

 shores at low tides. They were probably just approaching a late repro- 

 ductive season. Ripe eggs and motile sperms were obtained during late 

 summer in 1917, and also by July in 1918. The eggs are small, dark- 

 colored and opaque. 



Tonicella lineata Wood. Common forms along shores at low tide. 

 They yielded ripe eggs and motile sperms about the first of August in 1917. 



Mopalia muscosa Gould. Common form along shore at low tide. 

 They yielded ripe eggs and motile sperms near Aug. 1 in 1917, and also dur- 

 ing July in 1918. The eggs are small, opaque and very dark. 



Phyllophysia sp. A rare green-colored nudibranch found on the eel- 

 grass of Fisherman's Cove. Freshly laid egg masses were brought up 

 with the trawl on July 8, 1918. 



Aeolis sp. A very abundant nudibranch which lives on the eelgrass 

 and kelps. The animal is a small aeolid with grayish orange-tipped 

 branchiae. The egg masses were being deposited June 24 to July 16 in 

 1918. The height of the season is passed by this time, but occasional 

 specimens may be discovered laying eggs even later. The egg capsules 

 are deposited in whitish or pinkish gelatinous strings constricted some- 

 what like sausages. This string is wound in a zig-zag spiral from a cen- 

 tral starting point, producing a rosette which may be as much as 38 mm. 

 across. The animals may be brought into the laboratory, where they will 

 continue their egg laying. 



Anisodoris nobilis MacFarland. A common yellow nudibranch found 



