172 BATKACniDJi. 



I have examined the foramen which is found in the axil of this 

 species, and also of several others. It leads into a closed spacious 

 cavity, the inside of which is coated with a mncous membrane having 

 many reticulated folds. It appears to belong to tlie system of muci- 

 ferous channels, which is exceedingly develoi^ed in the fishes of this 

 family. 



The air-bladder is divided into two ovate lateral portions, com- 

 municating with each other by a narrow transverse tube ; the in- 

 ternal cavity is small, compared with the considerable size of the 

 organ ; this is due to the immense devcloj^ment of the muscle, fixed 

 to the side of each portion of the bladder. 



The genitals of the male show the peculiaritj' of two accessory 

 glandular organs being attached to the lower end of each of the 

 vasa deferentia. The one is compressed, externally similar to a 

 detached portion of the testiclej the other, situated more inferiorly, 

 is of elliptical shape and of a blackish-brown colour. 



Skeleton. — The skull is distinguished by its depressed, broad, 

 rounded form, being similar in this respect to that of Cottus gohio or 

 Silurus glanis. Tlie bones are well ossified, and the sutures gene- 

 rally very distinct. The crown of the skull is flat, twice as broad 

 as long, with the longitudinal crest scarcely visible, but emitting a 

 strong process joined to the neural spine of the first vertebra. The 

 posterior angles of the orbit are very prominent, and a transverse 

 muciferous channel, formed by two low ridges, runs from one angle 

 to the other. The orbital incisure is deep, sub-semicircular ; the 

 space between the orbits broad, flat ; a muciferous channel runs 

 along the orbital edge, and is bent inwards posteriorly to meet its 

 fellow from the other side (1/). Proefi-outal smaU, forming the 

 anterior angle of the orbit. The maxillary is long, slender, dilated 

 at the extremity ; the intei'maxillary is much shorter, slightly di- 

 lated posteriorly, and with the posterior processes of moderate length. 

 The mandible is low, strong, and very long, strongly bent inwards 

 towards the symphysis ; its muciferous channels arc little developed. 

 The head of the vomer is very broad, flat, anteriorly with a denti- 

 gcrous ridge ; palatine and pterygoid rather short and narrow. The 

 base of the cranium broad and quite flat. The epitympanic is large, 

 moveable, and so intercalated between the cranium, the operculum 

 and pr£Eoperculum, that the two latter bones are rather remote from 

 the cranixxm. The px^ajopercxxlxxm is very solid, and lai'ger than any 

 of the other opercular bones ; opercxxlxxm redxxced to three bony 

 radii, one of which is directed downwards ; the subopercxxlxxm is a 

 thin subtriangxxlar bone with a very strong ridge terminating in 

 a spine ; there are, besides, two mxxch nxox'e feeble ridges above it. 

 Infraoi'bital bones none. 



The sxxpx'ascapula and scapxda ax'e xxnited into a single, long, 

 sword-shaped bone ; coracoid rib-like : the radixxs and xxlna are very 

 short, whilst the cai'pal bones are elongated ; there are five of them, 

 the lower being the largest, the upper rudimeixtary. A very pecu- 

 liar styliform boixe (a pair of transformed ribs) extends from the 



