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

 dermoskeleton: such, e.g., as the rostrum, a. ; 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, 



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 ; ' but its homologue in Polypterus and Lepidosteus is subdi- 

 ; vided : and as the cartilaginous homologue of the epencephalic arch 



1 cxlv. (1846) p. 134. 

 O 2 



