236 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
compare hundreds of recent individuals. Atlantic Ocean ; ascending rivers of Eastern 
sea- board. 
2. A. brevirostris Le Sueur. Short-nosed or Blunt-nosed Sturgeon. 
Snout of half-grown individuals about one-third the length of the head, but propor- 
tionally wider at base than in the preceding species. Barbels usually arising a little 
nearer to tip of snout than to the mouth; not reaching mouth. Little or no difference 
between the form of the snout of the young and adult. No smooth area or fenestra on 
the top of the head of the young, between the parietal and frontal plates in the median 
line. Top of head less deeply concave between the eyes than the preceding species. 
Small dermal plates between the dorsal and lateral rows of scutes never tending to form 
oblique rows. Smaller dermal ossifications never tending to become lozenge-shaped, 
except on the sides of the upper lobe of the caudal fin. Dorsal, lateral, and ventral scutes 
not so closely crowded together as iu the preceding species. Average number in dorsal 
row, 10-11; iu lateral row, U5; iu ventral, 7-8; no preaual plates. Mesocentrous very 
early in life and in both sexes. The smaller dermal ossifications can scarcely be per- , 
ceived by the touch iu stroking the skin between the dorsal, lateral, and ventral rows ; 
of scutes in a fresh specimen. The species is in fact almost absolutely smooth over j 
the uuarmored parts of the skin when compared with the preceding. Mouth very 
wide; one-sixth wider iu proportion than in the common species. Dorsal, 33; anal, ! 
19-22; ventral, 17-21 ; pectoral, 30-31; caudal, 60; lower lobe of caudal loug. Peri- 
toneum dark browu, sometimes very dark, so that the viscera are nearly black when 1 
exposed upon opening the body cavity. Color of the skin above reddish brown; i 
nearly white below. 
This species occurs in the Delaware Eiver, whence the author of its name obtained 
it, somewhere about 1817. Since no absolutely distinctive characters have been yet 
offered by which the species might be recognized, it has afforded me great pleasure to 
supply this lacking information in the entirely new diagnoses given above of this as 
well as the common species. How much mere extensive thau the Delaware River its 
range may be I have no means of knowing, as I have found onlj^ one specimen, besides 
the five obtained by myself at Delaware City, which can be regarded as an authentic 
example of the species. This single specimen is in the museum of the Academy of 
Natural Sciences of Philadelphia, and consists of a dried and stuffed varnished skin 
marked iu white paint “84.” It agrees in everj' essential external particular with my 
own alcoholic specimens, but no record of its history is accessible amongst the cata* 
logues of the collections of that institution; all traces of the old manuscript cata- 
logues of the Bonaparte and the other old collections of fishes belonging to the 
Academy’s museum having been lost. I have, however, the strongest suspicion that 
this specimen, which is evidently very old, judging from its present condition, may be 
one of the originals of Le Sueur’s description published in the Transactions of the 
American Philosophical Society for 1818, though it does not correspond in minor 
details. That it may possibly be one of the types of the species seems tome not at all 
improbable, from the fact that Le Sueur was also one of the early members of the 
Academy and may have presented the specimen. There can be no doubt of its 
identity with the fresh specimens which I have made out to be the true A. brevirostris, 
and I have, therefore, incorporated it iu the list of material which I have used to 
frame the specific diagnoses of both forms. The figures of A. brevirostris on Plate I 
of Brandt and Ratzeburg’s work, is from a specimen belonging to the Bloch collection 
