No. l8.] TRIASSIC FISHES OF CONNECTICUT. 49 



The type species, attaining a total length of about 25 cm. 

 Length of head with opercular apparatus about equal to maximum 

 depth of trunk, and contained five times in the total length of 

 the fish ; depth of caudal pedicle somewhat less than one-half that 

 of the abdominal region. Cranial bones finely granulated. Pelvic 

 fins arising about midway between the pectorals and anal ; dorsal 

 and anal fins subequal in size, and almost completely opposed. 

 Scales smooth, none deeper than broad, those of the flank in 

 the abdominal region very finely serrated. 



The fin-formula given for this species in the original descrip- 

 tion by J. H. Redfield is as follows : 



D. 10-12; C. 30-40; A. 20-30; V. area 8; P. 10-12. 



In the additional notes on this form drawn up by the elder 

 Redfield, it is stated that " the pectoral fins are of an elongated 

 form, and are strengthened on the anterior margin by one or two 

 large and partly flattened rays, to the front of which the fringe 

 of fine raylets [fulcra] is attached. Owing to this peculiarity 

 of structure, the smallest section of the pectoral fin will often 

 serve to identify this species." 



Although the form of body in this species is usually more 

 slender than in C. redfieldi, it sometimes happens that distorted 

 specimens, in which the anterior part of the trunk has become 

 " shortened up " by mechanical deformation, simulate the deeper- 

 bodied species in outline and general proportions. Conversely, 

 also, the greater depth of body in C. redfieldi as compared with 

 the genotype is often obscured by the familiar hazard of vertical 

 compression, a circumstance which has frequently led to a con- 

 fusion of the two species. Indeed, this very circumstance happens 

 to be illustrated in the case of one of the original cotypes upon 

 which the species was established by the younger Redfield; and 

 so impressed was Newberry with the idea that the depth of 

 body had become reduced by fortuitous agency that he actually 

 propbsed to cancel the specific name bestowed upon it by the 

 original author, because, as he avers, for a fish which " in its 

 normal condition has nearly the outline of the shad . . . 

 the name of Caiopterus gracilis is inappropriate and conveys a 

 false impression." 



