158 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
This species is well represented in the collection, there being 7 specimens 7 to 8 inches long from 
Mujeres, Island, 7 specimens 8 to 9.5 inches long from Montecristo, 7 specimens 6.75 to 8.25 inches long 
from Chichen Itza, and 3 specimens 3.5 to 4 inches long from Progreso. It is easy to distinguish the' 
specimens from any of these localities. Those from the salt or brackish waters at Mujeres Island are 
shorter, plumper, and decidedly darker than those from either of the other localities; the black bars 
are very distinct, as is also the caudal ocellus. The specimens from Montecristo are more slender 
and the color very much paler; the black vertical bars are in each case quite indistinct, in some 
instances being almost or quite lost. The black caudal spot is less black and the white border more 
evident. The 7 specimens from the cenote at Chichen Itza are intermediate in color between those 
from the two other places, and are considerably more slender. They have an emaciated, starved 
appearance, which is doubtless accounted for by the fact that they had been caught from the cenote 
and kept in a trough or small artificial inclosure, presumably without sufficient food, for some time 
previous to coming into Mr. Nelson’s possession. 
Fig. 7 . — Iieros urophthalmus Gunther. 
Although it is easy to pick out the individual fish from any one of these localities, we do not find 
any structural differences of value. The color differences are due simply to the character of the water 
in which they were found. The difference in form is simply a question of food supply. Had all 
received the same food or in the same amount, these differences probably would not have appeared. 
52 . Spheroides marmoratus (Ranzani). Swell-fish. 
One specimen, 10.75 inches long, from Cozumel Island. 
53 . Spheroides testudineus (Linnaeus). Swell-fish; Puffer. 
One specimen, 9 inches long, from Mujeres Island. Head 3; eye 8; snout 2; interorbital 2.5 in head, 
1.3 in snout; D. 8; A. 6. No cirri, no prickles, but many pores over most of anterior half of body. 
54 . Philypnus dormitor (Lacepede). Guavina. 
Two specimens, 6 and 10.5 inches long, from Teapa. Head 3.6; depth 6.6; eye 7.5; snout 3.25; 
maxillary 2.33; interorbital 4.87; preorbital 7.5; D. vi, 10 or 11; A. i, 8; scales about 60,-22. 
