300 PROCEEDINGS OF THE CALIFORNIA 



Bridges, probably from the coast of Central America ; but the identification of 

 the exact locality and the species of cetacean from which it was obtained, was 

 prevented by the premature and lamented decease of that energetic fit'ld nat- 

 uralist. This species was obtained from the Humpback by Capt. Scammon at 

 Monterey, Cal. 



CoYonula diadema ? Lam. 



It is quite possible that the species here indicated under the above name, may 

 be distinct from the true Atlantic diadema, but materials for exact comparison 

 are wanting, and the figures given by Reeve and others very closely resemble 

 the form before me. The radiating ridges are six in each group, often slightly 

 bifurcated at their bases, and strongly sculptured with transverse, fluctuating, 

 slightly elevated beaded lines. The interspaces are sharply transversely grooved. 

 The superior membranous surface is brown, the pallium or hood surrounding the 

 cirri is slightly purplish. The scuta are subtriangulate, with the posterior pro- 

 longation longest, slightly keeled above, with sharply pointed adjacent umbones 

 at the anterior angle of the occludent margin. No vestiges of the terga are 

 present. Adult specimens are over two inches in diameter at the base In such 

 a specimen the dimensions of the scuta are as follows: Ion. occludent margin, 

 .215 in.; posterior margin slightly arcuated, .28 in.; anterior margin, .175 in.; 

 color of scuta, white ; concave below, stout, solid. This species has been ob- 

 tained from the Humpback whale (M. versabilu) from Behring Strait to the 

 Gulf of California, and may also be found on other species. It is especially 

 abundant on the flippers and on the under lip of these animals. 



Cryptolepas, n. g. 



Scuta and terga both present, minute ; valves six ; externally produced be- 

 low the surface of the whale's skin in thin radiating laminae, with their planes 

 perpendicular to the vertical axis of the animal, and bifurcating and enlarged 

 toward their distal edges. Parasitic on Cetacea. 



CRYPTOLEPAS RACHIANECTI, Ball. 



Valves, subequal, rostrum radiate, not elate. Lateral valves anteriorly alate, 

 posteriorly radiate ; carina alate, not radiate. Each valve internally trans- 

 versely deeply grooved, and furnished externally with six radiating laminae verti- 

 cally sliar()ly grooved ; the adjacent terminal laniiu;c of each two valves, coa- 

 lescing to form one lamina of extra thickness; all the laminaj bifurcated and 

 thickened toward their outer edges, with two or more short spurs on each side, ir- 

 regularly placed between the shell wall and the bifurcation. Superior terminations 

 of the valves (bluntly pointed ?) usually abraded, transversely siriate. Scuta sub- 

 quadrate, adjacent anteriorly, very slightly beaked in the middle of the occlu- 

 dent margin ; terga subquadrate, small, separated from the scuta by intervening 

 membrane; both very small in proportion to the orifice. Membranes very thin 

 and delicate, raised into a small lamajllaj between the opercular valves. All the 

 calcareous matter pulverulent, and showing a strong tendency to split up into 

 lamina3. Antero-posterior diameter of large specimen 1.G2 in.; do. of orifice, 

 .03 in.; transverse diameter of orifice, .58 in.; Ion. scuta, .17 in.; lat. do. .08 in.; 



