135 



Add to p. 370 of Volume IV. :— 



The fish described by Johnson as Chiasmodus niger belongs to the 

 Gadoid family, in which it may form a separate group characterized 

 by its naked body. 



22. CHIASMODTJS. 



Chiasmodon, Johnson, Proc. Zool. Soc. 1863, p. 408. 



Body elongate, compressed and tapering posteriorly, naked ; belly 

 pendent, its walls being quite membranaceous. Two dorsal fins and 

 one anal ; a separate caudal ; ventral fius rather narrow, with flat 

 base and several rays. Upper and lower jaw with two series of 

 large pointed teeth, some of the anterior ones being very large and 

 moveable ; vomerine teeth none ; each palatine bone with a series 

 of teeth similar to those on the palate. Chin without barbel. Bran- 

 chiostegals eight. 



Deep-sea fishes off the Island of Madeira. 



1 . Chiasmodus niger. 

 Johnson, I. c. 



D. 11 j 28. A. 27. P. 13. V. 5. 



Head rather compressed, elongate, with the crown flat ;. its length 

 is two-sevenths of the total (without mdal) ; its depth is rather 

 less than one-half of its own length ; the cleft of the mouth is ex- 

 ceedingly wide, the maxillary extending backwards to the angle of 

 the praeoperculum ; the lower jaw is somewhat longer than the upper, 

 and both are armed with long, pointed, widely-set teeth, nearly all 

 of which are moveable and can be laid backwards or inwards ; the 

 two anterior teeth of the upper jaw are very long, and cross each 

 other when in rest; the three anterior pairs of the lower jaw are 

 likewise prolonged, the third pair being the longest ; also the palatine 

 has a longer tooth in front, but this is fixed and not moveable. The 

 eye is of moderate size, two-ninths of the length of the head, rather 

 shorter than the snout, and equal to the width of the interorbital 

 space ; it is situated above the anterior half of the maxillary bone. 

 The hind limb of the praeoperculum descends backwards in so oblique 

 a line as to be nearly parallel to the scapulary. Gill-opening ex- 

 ceedingly wide, the gill-membranes being joined to the isthmus for 

 a short distance only ; pseudobranchiae none ; gills four, narrow. 



The body and tail are low, but the abdomen is very extensible and 

 pendent. Lateral line distinct as a longitudinal groove. The first 

 ■ dorsal fin commences above the humerus and is composed of very 

 delicate rays ; the length of its base is contained twice and one-third 

 in that of the second dorsal ; the anterior rays of the second dorsal 

 are well developed, whilst the posterior are very feeble. The anal fin 



2 f 2 



