390 University of California Publications in Zoology. [Vol. 4 



previously described by Claparede and Lachmann, or Gourret ; 

 nor did they call attention to the short forms of this species 

 which result from autotomy. When this phenomenon of auto- 

 tomy is borne in mind we may utilize Claparede 's and Lach- 

 mann 's description and revive their name for this well defined 

 species. 



Ceratiimi hiceps is a large species differing from C. fusits, 

 and C. seta, in its greater length, and from C. extensum in the 

 presence, uniformity, of a right antapical horn or its truncated 

 stump, in its larger midbody and in the less curved, slightly de- 

 flected, left antapical horn. 



Ceratium lamellicome nom. 



nov. 



Karsten (:05), p. 132, Taf. 19, figs. 9, 10, as C. tripos forma 

 dilatata. 



Kofoid (:07), p. 171, pi. 4, fig. 25, as C. dilatata (Karsten). 



Karsten (:07a), Taf. 48 (14), figs. 10a, 10b, as C. tripos platy- 

 come Daday. Karsten 's Taf. 51, figs. 4a, 4b, also called by 

 him C. tripos platycorne Daday, is the typical C. platycorne. 



Kofoid (:08), p. 185, fig. 28, as C. lamellicome. 



This is a small species of the C. platycorne group, with the 

 antapicals expanded into a thin sheet in the plane of the three 

 horns. It differs from the true C. platycorne in its smaller size 

 and relatively shorter aJntapicals which are also narrower with 

 a more regular curvature and a more uniform width throughout 

 their length. They lack the characteristic swelling found on the 

 median margin of the antapicals of C. platycorne. Karsten 's 

 earlier figures ( :05), designated by him as C. tripos forma dila- 

 tata, are in my opinion C. lamellicome. His later figures ( :07) 

 are in part (Taf. 48, figs. 10a, 10b), of the C. lamellicorne type 

 and in part (Taf. 51, figs. 4a, 4b) of the type originally described 

 by Daday ('88) as C. platy cornis. On the grounds above stated 

 I regard the two species as distinct. 



In his earlier paper Karsten ( :05) makes no mention of the 

 species described by Daday and we are left without any evidence 

 in his brief descriptive text as to whether or not he regarded the 

 two forms as distinct. In his later paper ( :07, p. 406) he dis- 

 cusses the question and concludes that his forma dilatata is only 

 a young form of C. platycorne, in which the antapicals have not 



