614 



ANATOMY OF VERTEBRATES. 



427 



39- 



into their nursery when danger threatens. 1 In Syngnathus 



ophidian the male carries the eggs under the flat abdomen in cells 



placed lengthwise in three rows. 2 In the 

 male Hippocamp the marsupium is subeau- 

 dalj opening by a vertical fissure just below 

 the vent. 3 In the Holconoti the young ac- 

 quire full developement, perfect gills, and a 

 size one third that of the parent, before 

 quitting the ovarian marsupium. 4 



Both Salmon and Trout excavate the 

 gravelly bed which they select for spawning ; 

 and the ova may be found from one to two 

 feet deep in this stony nest. The Stick- 

 leback (Gastcrosteus aculeatus) fabricates a 

 more artificial nest. Aristotle signalises the 

 Phycis, since recognised as a Mediterranean 

 species of Gobius, as the only sea-fish that 

 makes a nest and deposits its spawn therein. 

 Olivi confirmed the statement, and describes 

 the nest as being composed of sea-weeds 

 (alga? and zostera), adding that the male fish 

 guards the female during the act of oviposi- 

 tion, and the young fry during their deve- 

 lopement. 5 



Dr. Hancock has observed similar habits 

 in certain fresh-water Siluroid Fishes of De- 

 merara called ' Hassars,' which belong to the 

 genus Callichthys : the Round-headed Has- 

 sar forms its nest of grass ; the Flat-headed 

 Hassar of leaves. ' They are monogamous : 

 both male and female remain by the side of, 

 the nest till the spawn is hatched, with as 

 much solicitude as a hen guards her eggs, 

 and they courageously attack any assailant. 

 Hence the negroes frequently take them 

 by putting their hands into the water close 

 to the nest ; on agitating which, the male 

 Hassar springs furiously at them, and is 

 thus captured.' 6 



§117. Fecundation of Reptiles. — Sala- 

 manders, Newts, Frogs, and Toads are generally apt for breeding 



1 Eckstroem (1831), quoted in xxxix. ii. p. 327. 



2 xx vol. v. p. 67, prep. no. 3229. 8 lb. no. 3223. 4 ccexxxv. 

 1 XXIII. t. xii. p. 6. fi cccxxvi. p. 244. 



Marsupial pouch of Syngnathus 

 acus. 





