1909.] NATURAL SCIENCES OF PHILADELPHIA. 289 



June 20, 1905; one small example dredged Delmonte wharf , July 12, 

 1904. 



These specimens appear to belong to the above-named species, 

 although Miss Bush's species of Sabella are not clearly differentiated 

 in the brief descriptions. The spots on the branchiae are usually five, 

 fairly regular in arrangement, but varying much in intensity and the 

 degree to which they extend on to the gill filaments. The number 

 of rachises varies from IS to 22 on each side. The segments of one 

 counted number 70, 8 of which are setigerous thoracic. 



Distylia rugosa Moore. 



Distylia rugosa Moore, Proc. Acad. Nat. Sci. Phila., 1904, pp. 499-501; 

 PI. XXXVIII, figs. 3S-41. 



Besides the type and cotype from which this species was originally 

 described several additional specimens, all taken between tides at 

 San Diego, occur in the collection. 



The specimens are of various sizes, the largest measuring in its 

 contracted state 105 mm. long, of which the gills are 30 mm., and 

 11 mm. wide. In the different specimens the branchial rachises vary 

 in number from 24 in one 40 mm. long to 68 on each side of the large 

 specimen. In no case are any of the rachises forked. The branchial 

 bases make about 1% turns. The eyes referred to in the original 

 description are mere specks and dashes of pigment arranged in two 

 series which may coalesce into more or less broken lines or be totally 

 absent. 



Sometimes the branchiae are of a nearly uniform wine brown with 

 regular but obscure transverse pale bands ; in other cases they may be 

 light or dark brown, irregularly mottled with pale. The gill bases are 

 uniform deep brown. At the dorsal end of each abdominal torus is a 

 very deep and conspicuous brown spot, from which a narrow brown 

 line runs along the torus for its entire length, ending in a small spot 

 at the ventral end. The ventral plates are very deep purplish brown, 

 the body elsewhere pale brown. 



The largest specimen has the collar region so relaxed that the r mouth 

 parts are well displayed. The tentacles are narrowly lanceolate with 

 a small divergent basal lobe and reach barely to the distal border of 

 the branchial base. 



Pseudopotamilla brevibranchiata Moore. 



Pseudopotamilla brevibranchiata Moore, Proc. Acad. Nat. Sci. Phila., 1905, 

 pp. 559-562; PL XXXVII, figs. 8-14. 



Two specimens taken at "big tide pool/' Monterey Bay, present 



several interesting divergences from the types. 



19 



