HIGH SCHOOL ZOOLOGY. 



67 



A great many of the South Americau Siluroids have a very complete 

 exoskeleton. CaHichtliys and Loricaria (Fig. 22) are representative 

 genera ; they all appear to be very tenacious of life out of water, their 

 gill-cavities being arranged as in Doras. Aspredo is a singular genus 

 in which the female carries about the eggs attached to papillae of the 

 skin of the ventral surface, until they are hatched. 



Certain old-world tropical forms are provided with arrangements 

 better adapted than those referred to above for li\ang out of water. 

 Clarias, Saccobranclius and others have a recess projecting backwards 

 from each gill-cavity which can be filled with water. 



Fig. 22.— Mailed Siluroid, from South America. Loricaria cataphracta. J. 



(After Brehm.) 



9. A very large number of our fresh-water fishes belong to a 

 family nearly allied to the Siluroids, that of the Cyprinidae, 

 embracing the suckers, carps, goldfish, minnows, shiners, etc., 

 of which the suckers ai-e sometimes i-eckoned as an independent 

 family (Catostomidae). Although very diffei-ent externally 

 from the Siluroids (for they are generally scaled fishes and often 

 brillantly coloured), yet they share the peculiar structure of 

 the anterior vertebrse and air-bladder, which is present in 

 that group. The gill-cover has all the four bones, but thei'e is 

 no adipose fin. There are no teeth on the jaws, but the 

 pharyngeal bones are well provided therewith. On the roof of the 

 mouth in front of the first gill there is a rudimentary fifth gill 

 called a pseudobranch, through which only arterial blood 

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