MYCTOPHIDAE 319 



number of nominal species are probably included among them. Brauer [1906, ' Valdivia ' 

 Tiefsee-fisc/ie, pp. 150-251], who included all the species in a single genus, Myctophiim, 

 was the first to reduce the chaos to some sort of order, and in quite recent years other 

 investigators have added still further to our knowledge of the group. In 1928 Parr 

 [Bull. Bingham Ocean. Coll. iii (3), pp. 49-156] published a complete synopsis of the 

 four genera, based on the collections made in the Western Atlantic and West Indies by 

 the 'Pawnee', and described a number of new species. His keys to the species have 

 proved useful in determining many of the ' Discovery' specimens, and as a groundwork, 

 but, as many of the types of the species preserved in various museums and institutions 

 were inaccessible to him, these keys are necessarily somewhat tentative. In the same 

 year Taning [Vtd. Medd. Dansk nat. For. 86, pp. 49-69] published a preliminary synopsis 

 of the species of the North Atlantic, and he is at present engaged in studying the large 

 amount of material obtained in this and other regions by the ' Dana'. This synopsis has 

 proved of great value and interest, since, in addition to the 'Dana' material from the 

 Atlantic, Taning has examined some specimens from the Gulf of Panama and from the 

 Malay Archipelago, and has also studied most of the type specimens of these genera 

 preserved in various European and other museums. In a recent paper [1929, Ann. Mag. 

 Nat. Hist. (10), IV, pp. 510-15] I have published brief notes and descriptions of certain 

 specimens in the British Museum collection, as a supplement to the works of Parr and 

 Taning. In the present report I give for each species a reference to the pages and 

 figures in the papers of Brauer, Parr and Taning. 



Genus Myctophum, Rafinesque, 1810 



The group of species distinguished by having no Pol photophores, and the AO 

 forming a single continuous series, may be arranged as follows: — - 



I. Lens of the eye excentric, dorsal. 



A. The two first SAO and the two Pre separated from one another by wide interspaces. 



I. parallelum, Lonnberg, 1905 



B. The first two SAO and the two Pre normally spaced. 2. arcticum (Liitken, 1892) 

 II. Lens of eye normal, central. 



A. Depth of body less than 3 in the length, length of head 2 J to 3 ; eye 1 1 to 2! in head. AO 

 10-12. 3. rissoi {Cocco, 1829) 



B. Depth of body more than 3 in the length, length of head 3 to 4; eye 2\ to 3 in head. 



1. No SAO photophores; AO 14-15, first two elevated. 4. anderssoni, Lonnberg, 1905 



2. 3 SAO photophores; AO 15-18, none elevated. 



a. Origin of anal just behind last dorsal ray ; dorsal commencing a little behind root of 

 pelvic; 2 PVO, close together and side by side. 5. tenisoni, n.sp. 



b. Origin of anal below dorsal, which commences well behind root of pelvic ; 2 PVO 

 placed one above the other. 



* Eye 2| to nearly 3 in the head ; posterior margin of maxillary truncate ; origin of 



anal below middle of dorsal. 6. antorcticiim (Giinther, 1878) 



** Eye 2j to 2-2" in head ; posterior margin of maxillary rounded ; origin of anal below 



posterior part of dorsal. 7. subasperum (Giinther, 1864) 



8-2 



