Subclass CHONDROPTERYGIL 



Skeleton cartilaginous ; no cranial sutures. From one to seven 

 external gill-openings on each side ; the gills are attached by their 

 outer edges to the skin, with a gill-opening intervening between 

 each two lamina) ; no gill-cover. Two or more series of valves at 

 the conus arteriosus. The optic nerves, although united, do not 

 decussate, or do so only slightly. Body with vertical and paired 

 fins, the posterior pair abdominal ; caudal fin with an eloDgated 

 upper lobe. Intestines with a spiral valve. Male sex with intro- 

 mittent organs attached to the ventral fins. Ovaries containing 

 large ova, which are fertilized, and sometimes likewise developed 

 internally. Embryo with external deciduous gills. No air-bladder. 



This subclass includes the sharks, rays, and chiinaoras, and is 

 divided into two orders, the second of which does not appear to 

 have representatives in India. Geologically speaking, these fishes 

 existed prior to the Teleosteaus. 



Synopsis of Orders. 



Five to seven external gill-openings, 

 and no cartilaginous gill-cover. 

 Jaws distinct from the skull 1. PLAGIOSTOMATA. 



A single external gill-opening having a 

 rudimentary cartilaginous gill- 

 cover ; four branchial clefts inside 

 the gill-cavity. Palatal and maxil- 

 lary apparatus attached to the 

 skull 2. 1IOLOGEP1IALA. 



