FISHES OF CHESAPEAKE BAY 
315 
The spawning season at Beaufort, N. C., according to Smith (1907, p. 362), takes place in the 
spring. Welsh and Breder (field notes) found ripe fish at Atlantic City, N. J., from August 19 to 
25, 1920. Kuntz and Radcliffe (1918, pp. 105 to 109), who give an account of the embryology and 
larval stages, state that the species spawns (presumably at Woods Hole, Mass., for that is where 
these authors worked) in June, July, and August. The egg is described as being 1 to 1.15 milli- 
meters in diameter, lighter than sea water, slightly yellowish in color, but highly transparent. The 
incubation period at a temperature of 22° C. is given as approximately 60 hours. The newly 
hatched larvse are stated to be about 2.8 millimeters long, and to have grown to a length of 3.1 to 
3.4 millimeters in five days. In young fish, 8 to 10 millimeters long, the dorsal, anal, and caudal 
fins had become well differentiated, and the free rays of the pectoral fins, characteristic of the 
genus, were already present. Young fish 25 to 30 millimeters in length have all the fins well formed, 
the head shows the bony structure characteristic of the adult, and the fish are gradually acquiring the 
diagnostic characters of the species. 
The following catches of young fish were made in the Chesapeake: December, 2 fish, 48 and 
50 millimeters (2 inches); March, 2 fish, 46 and 53 millimeters (2 inches); April, 48 fish, 33 to 82 
millimeters (IJ-fj to 3 inches); May, 10 fish, 45 to 68 millimeters (1$4 to 2 inches). 
This species is reported to reach a maximum length of 15 or 16 inches; rarely, however, exceed- 
ing a length of 1 foot. No individuals among the numerous ones taken in Chesapeake Bay exceed 
a length of 11% inches. The species is very common in Chesapeake Bay, occupying both shallow 
and deep water, apparently being more numerous in deep than in shallow water. It was taken in 
considerable numbers throughout the year in the beam trawl, which usually was hauled in the 
deeper waters of the bay. The greatest depth recorded in the log for this species is 23 fathoms. 
This sea robin is not used for food and has no commercial value. 
Habitat.-— Bay of Fundy to South Carolina; common from Cape Cod to Cape Lookout. 
Chesapeake localities. — (a) Previous records: Mouth of the Potomac River, Md., Gunston 
Wharf, Old Point Comfort, Hampton Roads, Norfolk, Ocean View, and off Cape Henry, Va. 
(b) Specimens in collection: Many localities, from Love Point, Md., to the mouth of the bay. 
173. Prionotus affinis sp. nov. Sea robin. 
Type No. S7654, U. S. National Museum; length 203 millimeters; off Kent Island, Md. 
Head 2.95 to 3; depth 5.55 to 5.65; D. X-13; A. 12; scales about 108. Body quite slender, the 
depth under spinous dorsal nearly equal to the width, somewhat compressed posteriorly; head mod- 
erately large, quite strongly depressed; snout rather long, depressed, its length 1.95 to 2.05 in head; 
eye 5.2; interorbital deeply concave, 6.15 to 6.9; mouth rather small, horizontal; lower jaw included; 
maxillary not nearly reaching eye, 2.9 to 3 in head, 1.4 to 1.55 in snout; teeth as in P. carolinus; gill 
rakers rather short, 11 or 12 somewhat developed on lower limb of first arch; scales small, ctenoid, 
somewhat reduced in size on chest; spines and striations on head somewhat more prominent; other- 
wise as in P. carolinus, the preopercular spine reaching well beyond base of humeral spine; serrations 
on margin of snout quite prominent; a straight, shallow furrow across the cranium just posterior to 
the eyes; dorsal fins separate, the first composed of rather strong, stiff spines, the third and fourth of 
about equal length, 2 to 2.1 in head, somewhat longer than the longest soft rays, not reaching 
beyond the tips of the posterior spines when deflexed nor to origin of second dorsal; caudal fin with 
rather deeply concave margin, the rays of upper lobe slightly the longest; anal fin similar to second 
dorsal but not quite as high, its origin slightly behind that of the second dorsal; ventral fins moder- 
ately developed, inserted under and somewhat posterior to bases of pectorals, reaching somewhat 
past origin of anal; pectoral fins of moderate length, reaching about opposite base of the sixth anal 
ray, 2.4 to 2.45 in length of body, the free rays distally with membranous expansions. 
Color in alcohol brownish above, with small darker brownish markings, but no large blotches ; pale 
underneath; gill membranes dusky; dorsal fins brownish, with pale to white spots or longitudinal 
markings; a black spot between the fourth and fifth dorsal spines; caudal fin uniform brownish; anal 
fin pale, with a dark band across middle; ventral fins pale; pectorals dusky, the lower free rays pale. 
Two specimens, 203 and 325 millimeters (8 and 12^4 inches) in length, occur in the collection, 
which are closely related to P. carolinus, differing, however, in the more slender and more elongate 
body, slightly smaller mouth, somewhat larger and more prominent sculpture of the head, and in 
color. The furrow on head just posterior to the eyes is straight and not bent backward as in P. 
