DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 53 



Family MICROSTOMID.^. 



Microstomatoidoe, Gill, Cat. Fish. E. Coast, N. A., 1861, 54. 

 Microstomida; Gill, Arr. Fam. Fishes, 1872, 16. 



The family Microntomiilw, although never formally defined by Dr. Gill, is evidently a 

 valid one, separated from Argentinidw by the much smaller number of branchiostegal 

 rays, only three or four, instead of six to eight, as in Argcnthiida: The advanced position 

 of the ventrals is a collateral character. 



MICROSTOMA, Cuvier. 



Microstoma, CuviER, Ri-gue Animal, Ist etl., 1817, ii, 184; 1829, il, 285.— Gunther, Cat. Fish. Brit. Mus., 

 VI, 204; Challeuger Report, xxu, 218. 



Microstomids, with small mouth, small inter maxillaries., short and broad maxillaries. 

 Small teeth, in narrow series in lower jaw, and on head of vomer. Ventrals in front of dor- 

 sal. Caudal tin furcate, its base squamose. Branchiostegals, 3-4. Pyloric c;eca absent. 

 Air bladder large. Scales large, thin, silvery. Adipo.se tin absent in adults. 



"The evidence as to the bathybial habits of these small tishes," writes Giinther, "is 

 merely circumstantial. They seem to have the same vertical range as Argentina, but are 

 more rarely seen in collections, as the small size of their slender cylindrical body renders 

 their- capture very difficult." 



MICROSTOMA ROTUNDATUM, (Risso), Gu>fTnER. (Figure 59.) 



Gasteropelecus microstoma, Ris.so, Ichtb. Nice, 1810, •3.^6. 



Mlerof.toma micrastuma, Cl'ViHR, Rpgne Animal, ed. 1, 1817, II, 184; ed. 2, 1829, 285. 



Mirrosloma rotimdula, Risso, Eiir. Morid., 1827, III, 475, fig. xxxvi. 



Microstoma rotundatiim, Gi'XTilER, Cat. Fish. Brit. Mas., vi, 204. — Canestrini, op. cit., 130. 



Microstoma argnnteum, Cuvier and Valenciennes, Hist. Nat. Pois.s., xvm, .358, ]>1. 544. 



Body cylindrical, mouth sm:ill. Height of body 10 to 11 in length. Diameter of eye 2J in 

 length of head, the latter Si in total length. Ventrals midway from base of caudal and base 

 of pectoral. Adipctse tin usually wanting. Silvery. 



Radial formula: D. 9-11; A. 8; P. 8; V. 10; L. lat. 52. 



Known only from Nice and Sicily. It is placed among bathybial forms in deference to 

 the opinion of Dr. Giinther already quoted. The National Museum has a specimen (No. 

 40072) from Messina, sent by the Florence Museum, one of fifteen examples of this very 

 rare form, taken by Giglioli, September 25-28, 1875. 



We have had no opiiortunity of examining another Mediterranean form recently described 

 by Facciolii (Micmstumu oblltum, Facciohi, Naturalista Siciliana vi, 193.) 



MICROSTOMA GRCENLAXDICUM, Reinhardt. 



Microstomus gra:nlandicus, Reinhardt, Vid. Selsk. Naturvid. og Math. Afliaiidl., viii. 1841, Ixxi\'. 

 Microstoma groenlandiciim, GUnther, Cat. Fisli. Brit. Mus.. vi, 205. — Gill, Cat. Fish. E. C. N. Amer. 



"Height of body 10 in length. Length of head 5 in same. Ventrals under po.sterior 

 part of ventrals. Adipose tin (M)nspicuous." 



Radial formula: D. 11; A. 10; V. 10. 



This form was found at an early day in the waters of Greenland, but has not since been 

 observed. 



Family BATHYLAGID.^. 



BailujUgidir, Gill, Science, iii, G20, 1884. (Name only.) 



The family Balhylagidn- of Gill was formed for the genus Bathylagus of Giinther. This 

 genus includes five species of small tishes, one of them {B. atlmiiicm) occurring in the 

 Atlantic in de])ths as great as 2,040 fathoms, another (J>. antarcficitx) inhabiting the Ant- 

 ajctic Ocean at a depth of 1,950 fathoms, and a third {B. padficus\ occurring off the coast 



