CHAPTER IV. 
SYNOPSIS OF THE FAMILY HETEROPYGIL* 
BY F. W,. PUTNAM. 
HETEROPYGII Tellkampf, Muller’s Arch. f. Anat., p. 392, 
1844; and New York Journal of Medicine, v, p. 84, 1845. 
Hypsceidce Storer, Synopsis N. A. Fish, p. 435, 1846. 
Brain of ordinary development in all its parts, similar to that of 
Cyprinodontes and of about the same pi'oportions. Cerebral lobes 
larger than the nearly round optic lobes. Cerebellum overlapping the 
posterior third of the optic lobes. Medulla oblongata broad, with 
well defined right and left sides. (On comparing the brains of the 
three genera the only difference noticed was that in Chologaster the 
cerebellum was not quite as large proportionally, but more elongated 
and not quite as wide as in the other genera, while the optic lobes of 
this genus with well developed eyes were no larger than in a Typh- 
lichthys of the same size.) 
Skeleton not studied. Gunther gives the vertebra3 as thirteen ab- 
dominal and nineteen or twenty caudal. The bones of the head are 
thin and mostly flattened as in the Cyprinodontes. Occiput slightly 
convex. 
Body compressed posteriorly. Head and anterior portion of body 
depressed, giving the form of a broad, flat head, with a compressed 
tail. 
Branchiostegal rays six in number and but slightly covered by oper- 
cular bones ; opercular opening large. 
Fins. Dorsal and anal nearly opposite and posterior to centre of 
body. All the fins except the ventrals well developed, with central 
rays longest and first rays simple. Pectorals close to the head, about 
in the middle of the sides. (Ventrals present in Amblyopsis, absent 
in Typhlichthys and Chologaster.) 
Mouth opening upwards, with lower jaw slightly projecting. Mar- 
gin of the upper jaw formed by the intermaxillaries. Maxillaries 
placed behind the intermaxillaries, with lower third broad and below 
the intermaxillaries. Several rows of fine teeth on the intermaxil- 
laries and lower jaw. (Teeth on palatines in Amblyopsis and Typh- 
lichthys, none on these bones in adults of Chologaster.) 
Scales. None on the head. Body closely covered with small, par- 
tially imbedded cycloid scales, irregularly arranged. 
Lateral line absent. 
From the Annual Report of the Peabody Academy of Science for 1871. 
(55) 
