806 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXVIII. 



While there is essential similarity in such characters, as to the 

 cranium there is consi<ler.'il)l(» dissimilarity between the pipe-fishes 

 and the sea-horses as will be evident from the accompanying tig'ures. 



The best known of these fishes are the typical sea-horses, but other 

 nieml)ers of the family are much less aberrant from the pipe fislies, 

 and indeed grade into them. There are in fact two distinct groups or 

 subfamilies, the Hippocampines and Solegnathines. 

 These difi'er in form and the form is determined 

 pai'tly by, or perhaps expresses, the development of 

 ridges of the body. 



The Hippocani])ines have the upper ridge of the 

 caudal region terminated forward under the dorsal 

 Hn, and the lower caudal ridge continuous with the 

 lateral ridge of the trunk; the nuchal plate is more 

 or less elevated, crowns the back of the head, and is 

 comiate with the preceding plate. 

 Two typical and nearly related ge- 

 nera {IJlppoadiijxis and Accntfo- 

 nura) show these characters in ])er- 

 fection; three others {Phyli<>]>fi'- 

 /•)/,i\ ]IaluchtJn/s^ and I*/i//rO(/i/)'i/.s) 

 share them in ditferent degrees. 

 The typical sea-horses {jr'qipocaitipuH) have the 

 trunk compressed and relatively deep backward, 

 the occipital region is surmounted by a sort of 

 "coronet," and the tail is I'obust and rolled in- 

 ward. The mature males have a pouch under the 

 fore part of the tail with a small opening or slit in 

 front. 



The likeness to the conventional knight of the 

 chessboard is nuich more marked than to a horse's 

 head; indeed, if a spirula-shell or roiled worm were 

 attached to the l)ase of a chess knight the sea-horse 

 would be wel,l imitated. The ancient name ITtp}- 

 pocainpax. is therefore ver^- apt, being derived 

 from the Greek }upj><>s, horse, and l'<iinpe^ worm 

 or caterpillar. But let no one be deceived by 

 superficial resemblance of parts. The head of 

 the fish and that of a horse are essentially ho- 

 mologous, but here real likcnivss ends; the con- 

 tracted part of the sea-horse does not correspond to the neck of a true 

 horse, but to the fore part of the abdomen, there being no true neck 

 in the fish; the lower part of the "neck'' of the fish is really the 

 hinder part of the al)domen, and the anus marks its hinder boundary. 

 The peculiar modification of the finless tail deprives it of its locomo- 



—.-Htk. 



Fig. o.— B k o a d-n o s e d 



P I P.E-F I S H (SlPHONO- 

 STOMATYPHLE). SKULL 

 FROM ABOVE SHOWING 

 DIFFERENCES FROM 

 SEA-HORSE. (A F T E R 



SCHAFF.) (For letter- 

 ing see Fig. 1.) 



