ANATOMY OF VERTEBRATES. 



195 



seen in the endoskeleton of the Batrachia. In the Trunk-fishes 

 (Ostracion), and Pipe-fishes (Syngnathus), the dermal scale bones 

 form a continuous coat of mail, like a tessellated quincuncial pave- 

 ment, over the entire body, as shown in the transverse section, 

 fig. 16, d n, dp, d h, and the endoskeleton is but little ossified. 

 The like is seen in the Hippocamps. Thus, in Pegasus draco, 

 fig. 124, with the exception of the small premaxillaries d, and 

 mandible , all the visible hard parts of the head are due to the 

 dermoskeleton : such, e.g., as the rostrum, ; the plates in which 

 the eyes are placed, b ; the gill-covers, h ; the median plate, g, 



124 



Dermoskeleton of the Flying Hippocamp (Pegasus) 



supporting the hyobranchial arches ; the zone, i, sustaining the 

 large pectoral fins ; and the hard case of the incubating pouch, 

 o, q. 



In the Ganoidei, parts of the exoskeleton coalesce with endo- 

 skeletal bones of the skull, especially the sclerogenous ones, while 

 others overlie the true cranial bones. Thus, in the Sturgeon, 

 the ganoid plate, marked d 3, fig. 125, simulates a superocci- 

 pital ; l but its hornologue in Polypterus and Lepidosteus is subdi- 

 vided : and as the cartilaginous homologue of the epencephalic arch 



1 CXLV. (1846) p. 134. 

 O 2 



