gill] 



THE LUMPSUCKER 



179 



Bumicrotremus has large tubercles closely but irregularly ar- 

 ranged, and the first dorsal remains developed through life. The 

 branchial apertures are much reduced. Four species are known, the 

 B. spinosus of the arctic Atlantic and the B. orbis, B. pacific us, and 

 B. brashnikowi of the northern Pacific. 



■■■^.. 



^ : -' G ...- 



Fig. 38. — Lcthotremus muticus. After Jordan and Gilbert. 



Fig. 39—Lethotremus azccr. After Jordan and Starks. 



Lcthotremus has no large tubercles, the skin being naked or with 

 few scattered spinules, and the first dorsal is well developed and 

 sustained by 6-8 slender spines. The branchial apertures are very 



