314 DISCOVERY REPORTS 



Regan (191 1) thought that Neosudis Castelnau (1873) might be a scopelarchid ; but Neosudis has a 

 dorsal fin of sixteen rays placed two thirds of the way back along the body, whereas the dorsal fin in the 

 Scopelarchidae has 6-10 rays and is placed about half-way down the body. As Parr (1928) has pointed 

 out, the genus is evidently not related either to the Scopelarchidae or Evermannellidae. 



Benthalbella Zugmayer (191 1) has already been considered: its status will be discussed below. 

 Turning to Promacheon Weber (1913), which was provisionally included by Parr (1928) in the 

 Scopelarchidae, this genus cannot be fitted into this family. The peculiar triangular tooth on 

 each premaxilla, the number, form and arrangement of the other teeth, the absence of teeth on the 

 palatines, the fin-ray formula (D. 14, A. 17-18, Pect. 15, Pv. 10) and the small number of lateral 

 line scales (c. 32), show that Promacheon has a character complex quite unlike that of the scopelarchids. 



Scopelarchoides Parr (1929) is defined has having two areas of abdominal muscles, one surrounding 

 the base of the pelvic fin, the other being an upper lateral musculature with a limited ventral extension. 

 Between these two areas the body-wall is transparent, for the peritoneum is only separated by connec- 

 tive tissue from the outer skin. The division of these muscles is very like that of Benthalbella larvae. 

 Chapman ( 1 939) noted that small specimens of Neoscopelarchoides dentatus have a translucent abdominal 

 cavity and that the abdominal musculature is fully developed only in the larger individuals. This sug- 

 gests that the fishes described as Scopelarchoides nicholsi were not completely developed. If this is 

 admitted, the differences between Scopelarchus and Scopelarchoides are clearly no more than dif- 

 ferences between different phases of development. The other characters which Parr (1929) has used 

 to define these two genera are nearly all osteological, involving the lesser development of various bones 

 (prootics, opisthotics, preorbitals and subopercula) in Scopelarchoides. Evidence from these characters 

 also indicates that Scopelarchoides Parr (1929) cannot be retained as a separate genus, and that it is 

 synonymous with Scopelarchus Alcock (1896). 



It is clear from this study that the scopelarchids can be divided into two genera only: (1) Scopelarchus 

 Alcock (1896) comprising the short-bodied species, in which the origin of the dorsal fin is in front of 

 the insertion of the pelvic fins (S. guentheri Alcock, S. nicholsi (Parr), and S. cavei sp.n.). (2) Neo- 

 scopelarchoides, comprising the long-bodied species having the origin of the dorsal fin behind the in- 

 sertion of the pelvics (Scopelarchus elongatus Norman, Neoscopelarchoides dentatus Chapman, N. dubius 

 sp.n. Benthalbella infans Zugmayer, and Scopelarchus linguidens Mead and Bohlke). 



Two names are available for the second genus, Benthalbella Zugmayer and Neoscopelarchoides 

 Chapman. Zugmayer (191 1) described Benthalbella infans in an Appendix to his report, since he was 

 unable to determine its systematic position, yet he did point out that there were certain resemblances 

 between his fish and Brauer's Dissomma anale. Remarking that, ' Ce poisson est tres jeune ou plutot 

 larvaire ', he none the less gave it a name because it was then unknown. 



Article 30 of the International Rules of Zoological Nomenclature, Section He, /?, states that: 

 ' Species which were species inquirendae from the standpoint of the author of the generic name at the 

 time of its publication ','... are excluded from consideration in determining the types of genera '. In 

 view of Zugmayer's uncertainty as to its systematic position and his admission of its larval character, 

 Benthalbella infans cannot be considered as a genotype. Neoscopelarchoides Chapman must thus be the 

 name for the second genus, genotype N. dentatus. 



The characters of the two genera and the main characters of the species are given in the following 

 key. The distribution of the better known species is also given. See also the chart on p. 313. 



There is a full description of the family characters in Parr's papers (1928 and 1929). 



