268 SILURID^. 



females, he afterwards, at p. 440, describes a male provided with the 

 same organs. 



I am enabled, by the examination of a female of A. batrachus, to 

 show that the fishes of this genus belong to those SUuroids which 

 take care of their progeny, and that the appendages mentioned 

 serve for the purpose of keeping the eggs attached to the belly of the 

 mother. The ovaria of the fish examined are two nearly empty sacs 

 ■with thick walls, as if the ova had just been excluded ; some of them, 

 which had not been developed, still remained between the folds of 

 the interior. The whole lower surface of the belly, thorax, throat, 

 and even of a portion of the pectoral fins showed numerous shallow, 

 round impressions, to which a part of the ova still adhered. The 

 latter are spread out in a single layer, and being globular bodies, 

 leave small interspaces between them. These interspaces are filled 

 up by the appendages mentioned, and the terminal dilatation of the 

 latter is of essential help in keeping the ova in their position. If the 

 pouches on the back of the Pijjct were shallowed to mere impressions, 

 and the walls between them severed into flaps, we should have the 

 same arrangement as in Aspredo. 



Having examined several mature males and females of Aspredo, I 

 come to the conclusion that only the females carry with them their 

 ova, and that they only are provided with those ajipendages. It is 

 more than probable that towards the spawning-time the skin of the , 

 lower parts becomes sjjongy ; that, after ha\ing deposited the eggs, 

 the female attaches them to it by merely lying over them ; and that 

 the spongy substance between the eggs is absorbed by the pressure of 

 the latter, except in the interspaces, where it remains in the form of 

 the appendages described. The eggs, however, are retained not only 

 by the latter, but they adhere to the whole surface of the hoUow, 

 although loosely. When the eggs are hatched, the excrescences dis- 

 appear, and the skin of the belly becomes smooth as before. 



The eggs have a diameter of from half to two-thirds of a line. 



1. Aspredo batrachus. 



Mystus no. 10, Artedi, in Seha, iii. p. 86. tab. 29. fig. 10. 



Aspredo batrachus, Linn. Mus.Ad.Fred. p. 7.3; Aman. Acad.'i.^. 311. 



tab. 1. fig. 5 (Aspredo) ; Gronov. St/st. ed. Gray, p. 137. 

 Siku'us aspredo, Linn. Si/st. Nat. i. p. 502. 

 Aspredo, sp., Gronov. ZoopJii/l. p. 102. no. 326. 

 Platystacus Ifevis, Itloch, viii. p. 58 ; £1. Schn. p. 373. 

 Aspredo Isevis, Ckiv. 6|- Val. xv. p. 431. 



B. 5. D. 5. A. 53-57. P. 1/7. V. 6. Vert. 7/59. 

 Upper jaw broad, spatulate, much projecting beyond the lower; 

 barbels eight : one belonging to the maxillary, and extending to, or 

 somewhat beyond, the gill-ojiening ; it is dilated into a broad mem- 

 brane at its base, to which another small barbel is attached ; the 

 third pair of barbels is inserted at the angles of the mouth, and the 

 fourth at some distance behind the third. Upper part of the snout 

 perfectly smooth ; eye minute. Each intermaxillary with a narrow 



