236 Phthinobranchii 
numerous in all warm seas, mostly living in shallow bays among 
seaweed and eel-grass. The muscular system is little developed 
and all the species have the curious habit of carrying the eggs 
until hatched in a pouch of skin under the belly or tail; this 
structure is usually found in the male. 
The Solenostomida.— The Solenostomide of the East Indies 
are the most primitive of these fishes. They have the body 
rather short and provided with spinous dorsal, and ventral 
fins. The pretty species are occasionally swept northward to 
Japan in the Black Current. Solenostomus cyanopterus is a 
characteristic species. Solenorhynchus elegans, now extinct 
(with the trunk more elongate), preceded Solenostomus in the 
Eocene of Monte Bolca. 
The Pipefishes: Syngnathide.—The Syngnathide are very long 
and slender fishes, with neither spinous dorsal, nor ventral 
fins, the body covered by bony rings. Of the pipefish, 
Syngnathus, there are very many species on all northern coasts, 
Syngnathus acus is common in Europe, Syngnathus fuscum 
along the New England coast, Syngnathus californiense in 
California, and Syngnathus schlegeli in Japan. Numerous 
other species of Syngnathus and other genera are found further 
south in the same regions. Corythroichthys is characteristic 
of coral reefs and Microphis of the streams of the islands of 
Polynesia. In general, the more northerly species have the 
greater number of vertebrae and of bony rings. Tuiphle tiphle 
is a large pipefish of the Mediterranean. This species was 
preceded by Tiphle albyi (Stphonostoma) in the Miocene of 
Sicily. Other pipefishes, referred to as Syngnathus and Cala- 
mostoma, are found as fossils in Tertiary rocks. 
The Sea-horses: Hippocampus.—8oth fossil and recent forms 
constitute a direct line of connection from the pipe-fishes to the 
sea-horses. In the latter the head has the form of the head 
of a horse. It is bent at right angles to the body like the head 
of a knight at chess. There is no caudal fin, and the tail in 
typical species is coiled and can hardly be straightened out. 
Calamostoma of the Eocene, Gasterotokeus of Polynesia, and 
Acentronura of Japan are forms which connect the true sea- 
horses with the pipefish. Gasterotokeus has the long head 
and slender body of the pipefish, with the prehensile finless 
