904. FISHES——CYPRINODONTID.&. 
Fundulus, and different in appearance, so that we feel reluctant to unite the two gen- 
era, although the technical differences are very slight. Species all American, Surface 
swimmers, feeding upon insects. | | 
The species are quite numerous, but have been little studied. 
The following article from the pen of John A. Ryder, on the develop- 
ment of a species of this genus is almost the only attempt at the study 
of the breeding peculiarities of the Cyprinodonts : 
‘¢ Since we have taken up our temporary residence at Cherrystone, Virginia, we have 
found this interesting genus of cyprinodonts in great abundance in fresh and brackish 
water streams, also in a fresh water pond in the vicinity, a few miles south of where 
our station is located. In the latter situation three forms have been collected, all of 
which are in breeding condition—we will not say spawning condition, as they do not, as ~ 
do most other fishes, commit their ova to the care of the element in which they live, 
but carry them about in the ovary, where they are impregnated and where they develop 
in a very remarkable manner. 
‘¢Of the manner of impregnation we know little or nothing, except the evidence 
furnished by the conformation of the external genitalia of the two sexes. In the adult 
male, which measures one and one-eighth of an inch in length, the anal fin is strangely 
modified into an intromittent organ for the conveyance of the milt into the ovary of 
the female; a tubular organ appears to be formed by the three foremost anal rays, but 
one which is greatly prolonged and united by amembrane. At the apex these rays are 
somewhat curved toward each other, and thus form a blunt point, but the foremost one 
of the three rays is armed for its whole length with ridges at its base and with sharp 
recurved hooks at its tip, the other two at their tips similarly with hooks, and between 
their tips are two small fenestra or openings which possibly communicate directly with 
the sperm ducts from the testes. The basal elements of the fins are aggregated into a 
cylindrical columnar truncated bony mass, which is prolonged upward into the cavity 
of the air-bladder for the distance of nearly the eighth of an inch; from it a series of 
fibrous bands pass to the dorsal and posterior wall of the air-bladder to be inserted in 
the median line. Whether this bony column serves to steady the fin in tke act of copu- 
lation, or whether it serves to give passage to the sperm duct, is an unsettled question — 
with the writer. The modified anal fin of the male measures a third of an inch in 
length. Other peculiarities of the male are noticeable—for instance, the more ab- 
breviated air-bladder or space which also occupies a more oblique position than in the 
female. The most: remarkable difference preseated by the male as compared with the 
female, however, is his inconsiderable weight, which is only 160 milligrames, while that 
of the gravid female is 1,030 milligrames or nearly six and one-half times the weight of 
the male. 
‘¢ The female, as already stated, is larger than the male, and measures one inch and 
three-fourths in length. The liver lies for the most part on the left side. The intestine 
makes one turn upon itself in the fore part of the body cavity and passes back along the 
floor of the abdomen to the vent. The air-bladder occupies two-fifths of the abdominal 
cavity, and at its posterior end the wolffian duct traverses it vertically, to be enlarged 
near the outlet into a fusiform urinary bladder of very much the same form as in many 
embryo fishes, as demonstrated by Professor Kupffer and myself. The ovary is a simple, 
impaired organ which lies somewhat to the right and extends from the anterior portion 
of the body cavity to the hinder end, and serves to fill up its lower moiety when fully 
developed. The ova, when full grown, are each enveloped in a sac or follicle supplied 
