EGYPTIAN ULEGTBICAL FISH 449 



borne about until the young hatch. They are probably 

 caught up after exclusion and fertilization. Some of these 

 eggs are half an inch in diameter. Dr. Day states that the 

 same habits occur in certain Indian species of Arius and 

 Osteogeniomg. A species of Arius was found by Stein- 

 dachner, at Panama, to carry its eggs in a fold of the skin of 

 its belly ; afterwards the males bear them about in their 

 mouth. 



The females of Aspredo have on the ventral surface 

 horny, stalked ca})sules, which contain eggs from one to two 

 millimetres in diameter ; the capsules disappear as soon as 

 the young hatch. 



ifalapierurus electrivus Lacepede, of the Nile, is electri- 

 cal, the electric cells forming a layer directly beneath the 

 skin and enveloping the whole body, except the head and 

 fins. The cells are minute, lozenge-shaped, about one and 

 a half millimetres in diameter. They are supplied by a 

 nerve from the spinal cord. The shock is comparatively 

 feeble, but sufKces for defence, '■' the fish being protected by 

 its electrifying coat, as is the hedgehog by its spines." 

 (Owen.) 



Order 4. Hcyplioplwri. — This order, first named and 

 characterized by Cope, deri\'es its appellation from the 

 Greek axvcpo'^, a bowl, and qikpoo, to bear, in allu- 

 sion to a peculiarity of the pterygoid bone, which is en- 

 larged, funnel-shaped, and excavated by a bowl-like cham- 

 ber which expands laterally and is covered by a lid-like bone. 

 The brain has a peculiar plicated organ over the cerebellum ; 

 the air-bladder is simple, communicating by a duct with the 

 intestinal canal. The order comprises two families, the 

 members (jf which inhabit the rivers of Africa ; they are the 

 MormyridcB, represented by a number of genera and sjiecies, 

 and the Ciymnarclddce, of which Gyiiinarclms niloticus is 

 the only known species. 



Order 5. Teleocephall. — These are our common types of 

 fishes, and are, whether we consider their individual struc- 

 ture or the number of specific forms, the most highly de- 

 veloped, i. e., specialized, of the class. The name is derived 

 from re'Afzos, perfect, and Kiq)aXr}, head, in allusion to tlie 



