REVIEW OF HIPPOCAMPUS — GINSBURG 541 



exists on the Atlantic coast is the greater difficulty of distinguishing 

 the two forms occurring there, while the two Mediterranean species 

 are more readily distinguishable and were consequently recognized 

 by nearly all more recent authors. 



The Atlantic short-snouted seahorse differs specifically from the 

 short-snouted Mediterranean species and is treated herein under 

 the name of H. europaeus. The other Atlantic seahorse is rather 

 long-snouted and is apparently specifically identical with the long- 

 snouted Mediterranean species, guttulatus, but the Atlantic coast 

 population diverges sufficiently to be recognized as a distinct sub- 

 species and is here described as multiannularis . 



The differences between the subspecies guttulatus and multiannu- 

 laris may be readily appreciated by a study of tables 1 and 2. It 

 will be noted that multiannularis has a distinctly higher caudal 

 segment count, the mode being at 39 instead of 38. To a lesser 

 extent it also averages a higher dorsal ray count and possibly a 

 higher pectoral ray count. In proportional measurements multi- 

 annularis has, on the average, a slenderer trunk, a sHghtly shorter 

 snout, a rather longer postorbital distance, and a shghtly longer 

 trunk and shorter tail, although there are usually more tail seg- 

 ments. The white spots in multiannularis are usually somewhat 

 coarser and more numerous. The tubercles and coronet are perhaps 

 not so well developed as in guttulatus, but these structures vary 

 greatly with age, and their variations in both subspecies remain 

 to be established more definitely. The two subspecies differ some- 

 what as hudsonius and punctulatus differ on the American coasts. 



The difference between multiannularis and its congener occurring 

 in the same region, europaeus, may also be gathered by a study of 

 tables 1 and 2, europaeus saliently differing in having fewer caudal 

 segments and dorsal and pectoral rays and a shorter snout, but the 

 exact degree of divergence between the two Atlantic seahorses remains 

 to be determined. Out of 24 specimens examined, representing both 

 forms, all were readily referred to their proper species or subspecies, 

 except one somewhat doubtful specimen, which is described in some 

 detail on page 542. 



Material examined and geographic distribution. — The origin of the 

 specimens on which the foregoing account is based is to some extent 

 uncertain and is here explained in detail. Dr. Carl L. Hubbs kindly 

 sent me a lot of 20 seahorses from the collection of the Michigan 

 University Museum of Zoology for study, three of them more or less 

 damaged, the other 17 in fair or good condition. This lot was 

 originally kept alive on exliibition in the New York Aquarium and 

 according to Dr. Hubbs came "supposedly from the Bay of Biscay." 

 In order to trace their origin more definitely I wrote to C. M. Breder, 

 Jr., associate director of the New York Aquarium, who replied that 



