All California species posses a photophore im- 

 mediately below the eye and slightly forward of 

 the eye's midline, a photophore above the posterior 

 extremity of the maxillary on a level with the eye, 

 and a photophore immediately behind the angle of 

 the preoperele. Other photophores are mentioned 

 in table 2. The photophores between the bases of 

 the. pelvic and anal fins have not been dealt with as 

 a separate imit because an exact dividing line be- 

 tween these and the anal-to-caudal group is diffi- 

 cult to determine in many fish. Generally, C. sig- 

 nata has four photophores between the pelvics and 

 anal and the other species have five. The first two 

 pairs in this group are markedly close-set in Cy- 

 clothone sp., while the interspaces are equal or 

 slightly greater posteriorly in the other species. 



KEY TO ADULTS OF THE CALIFORNIA AND BAJA 

 CALIFORNIA SPECIES OF THE GENUS CYCLO- 

 THONE 



I. Branehiostegal membranes without pigment except 

 for a thin line over all but a few of the most posterior 

 rays and along the upper and lower margins (fig. 14F). 

 Roof of mouth pigmented mainly along its midline. Gill 

 cavities nearly colorless. Gillrakers totaling less than 

 20 on the lateral side of the first gill arch. One or two 

 gillrakers at angle of first gill arch. 



A. Total gillrakers on lateral side of first gill arch not 

 more than 15 (usually 4+10). Only one gillraker at 



angle of first gill arch (fig. 14E) 



C. signata Garman. 



B. Total gillrakers on lateral side of first arch 17-19 



(the position of the medial rakers on the arch ac- 

 centuated by a thin pigment line). Two gillrakers 

 at angle of first gill arch (fig. 14D).__Cj/c7oi/ioHe sp. 

 II. Entire branehiostegal membranes and most of the 

 oral and gill cavities darkly pigmented (fig. 14G). Gill- 

 rakers more than 20 on the lateral side of the first gill 

 arch. Two gillrakers at angle of first gill arch. 



A. None of the teeth on the premaxillary directed 

 strongly anterioventrad ; generally, every third or 

 fourth of the oblique teeth enlarged ; canines con- 

 spicuous on premaxillary (fig. 14B). Entoptery- 

 goid teeth not confined to an anterior cluster (fig. 

 14C. C. catiina Gilbert. 



B. Teeth along posterior three quarters of maxillary 

 directed strongly anterioventrad, generally increas- 

 ing in obliqueness and decreasing in size anteriorly ; 

 no conspicuous canines on the premaxillary (fig. 

 14A). Entopterygoid teeth confined to an anterior 

 cluster. 



1. Branehiostegal photophores 8 or 9. Branehios- 

 tegal rays 12. Pigmentation dark brown and 

 usually persistent ; photophores relatively small ; 

 scale pockets conspicuous. C. atraria Gilbert. 



2. Branehiostegal photophores 10 or 11. Bran- 

 ehiostegal rays 14. Pigmentation light brown or 

 greyish ; photophores of relatively moderate size ; 



scale pockets not conspicuous. 



C. acclinidens Garman. 



32. Cyclothone canina Gilbert. 



Fifrures 13D. 14B. and 14C. 



60.60. H6204, (3) 24-61 mm.: 60.80, H6204, (1) 62mm.; 

 60.100, H6204, (4) 24-48.5 mm.: 60.140, H6204, (3) 24-49 

 mm.; 60.180, H6204, (6) 22-70 mm.; 70.200, H6204, (2) 

 24.5-63.5 mm.; 80.70, H6204, (1) 56 mm.; 86.92, C6303, 



Table 2. — Comparative morphological data for the five species of Cyclothone occurring off the coasts of California and Baja 



California 



646 



U.S. FISH AND WILDLIFE SERVICE 



