18 PROCEEDINGS OF THE NATIONAL MUSEUM vol.76 



LAMPANYCTUS NANNOCHIR Gilbert, 1891 



Myctophum mannochir Gilbekt, 1891 (part). 



Nannobrachium nannochir (part), Jordan and Eveemann, 1896; Gilbesst, 



1895. 

 Lampanyctus nannochir Gilbert, 1913, Parr, 1928. 

 f Myctophum {Lampanyctus) leucopsarum Brauer, 1906. 



Material investigated. Type lot No. 44291, U.S.N.M." 8 speci- 

 mens from off the coast of the State of Washington. 



In spite of the various, quite extensive discussions of its taxonomic 

 status rendered by Gilbert (1895, p. 399; 1913, p. 100, and 1915, p. 

 315, under L. leucopsarus) , subsequent to its original description 

 (Gilbert, 1891, p. 51), L. rvannochir has up to the present date re- 

 mained a very obscurely and unsatisfactorily defined species. After 

 an inspection of the type sample deposited in the United States 

 National Museum the author is able, however, to verify the specific 

 distinctness of Gilbert's species from the closely related L. leucop- 

 sarus Eigenmann and Eigenmann^^ as well as from all other forms 

 included in the genus Lampanyctus. The following description of 

 the type sample, of which only one specimen is sufficiently well pre- 

 served to show the arrangement and numbers of the photophores, 

 may serve for future identification. 



" A second type specimen (No* 1459 of tiie Leland Stanford Junior University Museum, 

 from the same haul as the type-sample in the U.S.N.M.) has also been assigned to the 

 species in a later publication by Gilbert (1895, p. 400), wherein a more restricted defini- 

 tion of L. nannochir is rendered. It is obvious, however, that the specimens of L. leucop- 

 sarus, with which species L. nannochir was at first confounded, must have become weeded 

 out of the type sample of the latter species, probably by Gilbert himself, subsequent to 

 the publishing of the original description, as no such specimens are found in the sample 

 to-day. 



" The author has had opportunity to examine the type of L. leucopsarua Eigenmann 

 and Eigenmann in the Museum of Comparative Zoology, Cambridge. This specimen differs 

 from the above-discussed type of L. nannochir in having the upper SAO and Pol only 

 about the length of one of their own diameters, or even considerably less (Pol), removed 

 from the lateral line ; by the presence of 4 Pre in an equally curved series, well separated 

 from the postero-anal organs ; and by the presence of 5 VO, the second being elevated 

 and advanced to a position nearly vertically above the first VO. No traces of a VLO 

 are found in the type of L. leucopsarus, and there seems to be no indication of such 

 organ ever having been present on the specimen. A comparison with the type of L. nan- 

 nochir might further suggest the possibility that the so-called VLO of the latter specimen 

 should actually be homologous with the second VO of the type of L. leucopsarus, this 

 organ having in the former species merely become further elevated and advanced to a 

 position slightly anterior to the vertical from the first VO. On the basis of this assump- 

 tion both species might be defined as having lost their VLO. The type of L. nannochir 

 must otherwise be defined as distinct from the type of L. leucopsarus in having only 4 VO 

 as compared to the unquestionable 5 VO of the latter, in direct contradiction of the com- 

 parative tabulation of the features of these two species given by Gilbert, 1895 (p. 399). 

 Other differences in proportions, etc., claimed by the said author could not be verified on 

 the type specimens, which, on the contrary, seem quite concordant in all measurements. 

 A thorough revision of the various collections referred to each of the respective species 

 is highly desirable to clear the confusion existing in all previous descriptions. The types 

 of both species agree in the practically rectilinear arrangement of the SAO, the lower 

 one of which is situated entirely behind the vertical of the last VO; and also in having 

 the Pre well separated from the postero-anal series. 



