570 TELEOSTEI chap. 



or slightly anterior to the anal. The skeleton of Alcpocephalus ^ 

 is remarkable for its feeble ossification. Epipleurals and epi- 

 neurals are present, and the bilateral division of the neural arch 

 remains perfectly distinct throughout the praecaudal region, both 

 halves being very loosely apposed. The air-bladder is absent. 

 Ventrals are absent in Platytroctes, and the snout is much pro- 

 duced in Avlostomatomorpha. 



Eleven genera are distinguished : — A, with scales : Alepo- 

 ceplialus, Conocara, Bathytroctes, Leptochilichthys, Narcetes, Platy- 

 troctes, Aulostomatomorpha. B, without scales : — Xenodermichthys, 

 Aleposomus, Lcptoclerma, Anomalopterus. 



Eepresented by about 3 5 species in nearly all the seas ; as 

 usual with deep-sea forms, individuals of the same species have 

 been obtained from stations very remote from one another. 



Fam. 19. Stomiatidae. — I would unite under this name the 

 Stomiatidae and Sternoptychidae of Giinther, an assemblage of 

 aberrant deep-sea Fishes which agree in having the maxillary 

 bone more developed than the praemaxillary, and beset with 

 teeth, a character which differentiates them at once from all 



Fig. 345. — MaJacosteus indicns. (After Giinther. ) 



other deep-sea forms of this sub-order, as well as from the 

 Scopelidae among the Haplomi. The ventral fins are usually 

 inserted very far back, and the number of their rays varies from 

 5 to 8. Contrary to what occurs in other groups of fishes, the 

 pectoral fins have a tendency to reduction, and actually disappear 

 in some genera, whilst the ventrals remain well developed ; when- 

 ever the pectoral fins are fully developed, as in Ifaurolicus, 

 Chauliodus, Astronesthes, and Photichthys, the mesocoracoid arch 

 is present.^ The form of the body varies exceedingly, even within 

 the smaller groups into which this family has been divided ; it 

 may be excessively short and compressed, or excessively elongate, 



1 A detailed description of the skull of Alcpocephalus rostratus has been given by 

 Gcgenbaur, Morphol. Jahrh. iv. Suppl. 1878, p. 1. 



2 As pointed out by Gegenbaur. These forms are, however, placed by Gill in 

 a division characterised by the atrophy or absence of the mesocoracoid. 



