30 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.84 



ATOPOCOTTUS,' new genus 



Genotype. — A topocottus trih ranchius. 



Preopercle armed with 4: well-developed spines, the upper one en- 

 larged and branched. Gill membranes broadly united, free from 

 isthmus. Branchiostegals 6. Teeth in cardiform bands on premax- 

 illaries, dentaries, vomer, and palatines. Gills 3 ; no filaments on last 

 .gill arch and no slit behind it. Gill rakers in the form of short 

 tubercles. Pelvics I, 2. Scales occurring on anterior part of lateral 

 line only, not extending beyond end of first dorsal. 



The affinities of this strange cottid are obscure. Its nearest rela- 

 tives are probably to be sought among the allies of Pseudohlennius. 



ATOPOCOTTUS TRIBRANCHIUS,* new species 



Figure 6 



Body slightly compressed throughout, suboval in cross section; 

 deepest under anterior part of first dorsal, the distance from origin 

 of first dorsal to pelvic base 1,6 (1.5-1.7) in head, width at dorsal 

 end of pectoral base 1.8 (1.6-2.0) in head. Anterior portion of body 

 together with head forming a suboval mass, from which the pos- 

 terior portion of the body extends with almost straight dorsal and 

 ventral contours to the caudal peduncle. At the junction of these 

 two body masses, just posterior to the anus, occurs a distinct break 

 in body outline. Least depth of caudal peduncle 2.4 (2.2-2.7) in orbit. 



Head 2.6 (2.5-2.7) in standard length; snout 1.7 (1.4-2.0) in orbit, 

 moderately steep, forming an angle of 70° (63°-75°) with chin, of 

 134° (122°-139°) with frontoparietal region. Lower jaw somewhat 

 shorter than upper, slightly included ; maxillary extending to some- 

 where between middle and posterior margin of pupil. Anterior 

 nostrils in short tubes; posterior nostrils without elevated margins, 

 indistinguishable from pores of lateral line system. Eye large, 

 diameter or orbit 2.5 (2.4-2.6) in head. Interorbital space flat, nar- 

 row, about 2.0 in posterior width of maxillary. Top of head very 

 gently concave. No free nasal spines and no spines on top of head. 

 Four preopercular spines; the upper one 1.8 (1.3-2.1) in orbit, 

 directed upward and backward, slightly curved, with a simple or 

 bifid tip and bearing one or two secondary spines on its upper mar- 

 gin; these, in turn, often bifid; the three lower spines simple and 

 sharp, their length about equal to interorbital width, the upper one 

 directed backward, the middle one backward and downward, the 

 lower one almost straight downward. Pores of head large; most 

 conspicuous are the series that occur along the ventral margin of 

 suborbital chain extending upward behind the eye, and the series 

 along the preopercular margin continued forward as the mandib- 



• From Stottoi, extraordinary + Cottus. 



* From TptXt, tb*fce-f /Spdi-xta, gills. 



