﻿REVIEW OF GENUS DOROSOMA — MILLER 



399 



13) dorsal rays, 24 to 31 anal rays, usually 17 + 10 or 17 + 11 ventral 

 scutes, and with a short dorsal filament. It is exceptional for the 

 genus in having a very large mouth. 



Table 7. — Proportional measurements of 21 specimens of Dorosoma chavesi, 



expressed in thousandths of the standard length 



(Superscripts indicate the number of specimens] 



Measurement 



Standard length, in mm 



Dorsal origin to tip of snout. . . 

 Pelvic insertion to tip of snout. 



Anal origin to caudal bnse 



Body: 



Greatest depth 



Great width 



Head: 



Length 



Depth.... 



Width 



Interorbital, least fleshy width 



Snout, length 



Eye, length 



Snout+eye 



Dorsal filament, length 



Dorsal fin: 



Basal length 



Depressed height 



Anal fin: 



Basal length 



Height.. 



Pectoral fin, length 



Pelvic fin, length 



Lower caudal lobe, length 



Caudal peduncle, least depth.. 



Mandible, length.. 



Upper jaw, length 



Laguna Jenl- 



cero C.N.n.M. 



Nos. 6928; 



14632-36 



Range 



123-142 

 535-561 

 454-485 

 385-407 



345-386 

 101-116 



306-327 



236-2C0 



121-136 



77- 94 



51- 64 



77- 95 



136-152 



129-160 



123-138 

 207-236 



285-305 

 100-112 

 201-223 

 120-130 

 282-327 

 105-115 

 110-124 

 91-105 



Aver- 



>»I36 

 547 

 471 

 395 



366 

 107 



319 



249 



127 



86 



56 



87 



144 



147 



129 

 217 



294 

 105 

 213 

 124 

 297 

 111 

 118 



Laguna San 

 Francisco 



C.N.n.M. 

 No. 5927 



Range 



110-125 

 545-564 

 472^92 

 369-400 



359-386 

 106-119 



331-343 

 259-265 

 123-139 



85- 92 

 59- 69 



86- 96 

 151-156 

 100-179 



129-139 

 232-250 



271-300 

 87-121 

 215-230 

 12.3-134 

 294-347 

 110-115 

 125-140 

 99-114 



« 117 

 557 

 483 



•384 



373 

 111 



337 

 262 

 131 

 89 

 66 

 91 

 154 

 •170 



134 

 243 



5 287 

 107 

 224 

 128 

 319 

 113 

 133 

 104 



Lake Managua 



C.N.H.M 



No. 5926 



Range 



84-137 

 568-588 

 497-549 

 320-353 



366-403? 

 119-140 



347-405 

 273-307 

 136-147 

 82- 94 

 71- 84 

 83-102 

 154-178 

 1507-192 



123-136 

 219-242 



235-265 

 103-136 

 203-245 

 124-146 



Aver- 



«108 

 579 

 530 

 341 



384? 

 132 



371 

 286 

 143 

 90 

 77 

 95 

 171 

 «171 



129 

 '232 



251 



« 119 



234 



131 



Fins broken 



100-108 

 122-165 

 112-130 



104 

 144 

 121 



Species total 



Range 



84-142 

 535-588 

 454-549 

 320-407 



345-403? 

 101-140 



306-405 



236-307 



121-147 



77- 94 



51- 84 



77-102 



136-178 



129-192 



123-139 

 207-250 



235-305 

 87-136 

 201-245 

 120-146 

 282-347 

 100-115 

 110-165 

 91-130 



Aver- 



81124 

 557 

 489 



»0 379 



3727 

 114 



336 

 262 

 132 

 88 

 64 

 90 

 153 

 18 157 



131 

 i»228 



"281 

 '»108 

 221 

 127 

 18 305 

 110 

 128 

 106 



Relationships. — As indicated in the diagnosis, and as shown in 

 table 5, the mandible and upper jaw are much elongated in chavesi. 

 These structural features are so distinctive that the relationships of 

 chavesi are not readily discerned. It might even be justifiably set 

 apart in a distinct subgenus. In addition, chavesi is distinguished by 

 its large head and eye, the posterior position of the dorsal, the broad 

 interorbital (table 5), and also by the reversal in growth pattern of 

 the dorsal filament (see section on "Changes with Growth"). As 

 demonstrated in tables 5, 7, 10, and 11, all these distinctive traits are 

 those of the juvenile gizzard shad. Thus these specific characters of 

 D. chavesi represent the retention in the adult of juvenile characters 

 and tend further to mask the relationships of this species. In the 



