﻿388 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loo 



reexamined. Eleven counts were made on all the species and, in 

 addition, 24 proportional measurements were made on each of the 

 three southern species. Material for an adequate study of body- 

 proportions in D. cepedianum was not available, but preliminary 

 study demonstrated that the so-called slender subspecies, D. c. exile 

 (Jordan and Gilbert, 1883), described from Texas, cannot be reliably 

 distinguished on the basis of body depth. 



In examining the number of scales and vertebrae in Dorosoma I 

 found a negative correlation. The scale numbers of the southern 

 species are greatly increased, whereas the vertebrae show a significant 

 decrease. Thus D. cepedianum, with 52 to 70 scales in the lateral 

 series, has 48 to 51 vertebrae, whereas the three southern species, 

 with 70 to 83 scales, have only 43 to 48 vertebrae (tables 3 and 4). 

 Study of much new material of the Pacific species, Dorosoma smithi, 

 has demonstrated that the number of anal rays increases from north 

 to south (table 9), a gradient reversed from the usual variation in 

 fishes. 



The following abbreviations are used in this paper: C.N.H.M.= 

 Chicago Natural History Museum; S.N.H.M. = Stanford Natural 

 History Museum; U.M,M.Z.=University of Michigan Museum of 

 Zoology; and U.S.N .M.=United States National Museum. 



METHODS OF COUNTING AND MEASURING 

 In counting the fin rays I have followed the procedure recommended 

 by Hubbs and Lagler (1947, pp. 9-10). The count for the dorsal 

 and anal rays is of the principal rays, the branched rays plus one 

 unbranched ray. This unbranched ray is usually the first ray reaching 

 to or near the tip of the fin. In advance of this ray are three, occa- 

 sionally two, rudimentary rays in the dorsal fin and two, rarely one, 

 in the anal fin. Occasionally the higher variant for the number of 

 dorsal rays is combined with the lower number (2) of rudimentary 

 rays; thus the third ray (usually a rudiment) is elongated to become 

 the first full-length unbranched ray. The last ray of the dorsal and 

 anal fins was always regarded as split to the base and counted as one 

 ray. In the caudal fin the count was made of the principal rays, 

 which are the branched rays plus two. All rays of both pectoral and 

 pelvic fins were counted. 



In the enumeration of the scales of the lateral series, the first scale 

 counted was the first one lying above the uppermost corner of the gill 

 opening. With the exception of the scales along the throat region, 

 this is the anteriormost scale on the body. By this method my counts 

 are somewhat greater than those usually given for Dorosoma, but I 

 believe that a more precise enumeration was obtained. The number 

 of scales between the dorsal and anal fins was counted along an 

 oblique line joining the origins of these fins. The scale count around 



