Miscellaneous. 239 



from which it was obtained was prevented by the premature aud 

 lamented decease of that energetic field naturalist. 



^ Coronida diadema ?, Lamk. 

 It is quite possible that the species here indicated under tlie 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 

 ridii,'es are six in each grouj), often slightly bifurcated at their bases, 

 and strongly sculptured with transverse, fiuctuating, 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 subtrian- 

 gulate, with the posterior proloiigation 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 spe- 

 cimen the dimensions of the scuta are as follows : — length of occludent 

 margin -21-5 in., posterior margin (slightly arcuated) -28 in., anterior 

 margin -175 in. Coloupof scuta white ; concave below, stout, solid. 

 This species has been obtained from the humpback whale (J/, versa- 

 hilis) 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 pro- 

 duced below the surface of the whale's skin in thin radiating lamina), 

 with their planes perpendicular to the vertical axis of the animal, 

 and bifurcating and enlarged toward their distal edges. Parasitic on 

 Cetacea. 



Type Cryptolepas rhachianectis, Dall, n. sp. 



Yalves subequal, rostrum radiate, not alate. Lateral valves ante- 

 riorly alate, posteriorly radiate ; carina alate, not radiate. Each valve 

 internally transversely deeply grooved, and furnished externally with 

 six radiating lamina? vertically sharply grooved, the adjacent ter- 

 minal lamina) of each two valves coalescing to form one lamina of 

 extra thickness ; all the lamina; bifurcated and thickened toward 

 their outer edges, with two or more short spurs on each side, irregu- 

 larly placed between the shell-wall and the bifurcation. Superior 

 terminations of the valves (bluntly pointed ?) iisually abraded, trans- 

 versely striate. Scuta subquadrate, adjacent anteriorly, very slightly 

 beaked in the middle of the occludent margin ; terga subquadrate, 

 small, separated from the scuta by intervening membi'ane ; both very 

 small in proportion to the orifice. Membranes very thin and deli- 

 cate, raised into small lamellae between the opercular valves. AU 

 the calcareous matter pulvenilent, and showing a strong tendency to 

 split up into lamina). Antero-posterior diameter of large specimen 

 l-(>2 in., ditto of orifice •(53 in. ; transverse diameter of orifice -58 in. ; 

 length of scuta -17 in., breadth -08 in. ; length of terga -07 in., breadth 



