76 H. J. VAN CLEAVE 
Genus Rhadinorhynchus Liihe ro1t. 
The genus Rhadinorhynchus was created by LUHE (1911) to include the 
single species Rhad. pristis which occurs in fishes, chiefly of the Mediterranean. 
The addition of another species, had. horridus from Egypt, and the recogni- 
tion of the phylogenetic relationship existing between these two species and 
LINTON’s Lchinogaster sagittifer, caused LUHE (1912) to suggest the possible 
justification for recognition of a sub-family Rhadinorhynchinae. This sub-family 
was definitely recognized by the present writer (VAN CLEAVE, 1918) in a paper 
which placed three additional species from North America within the same 
subfamily. 
Rhadinorhynchus selkirki, xew sfecies. 
(Figures 1 to 4.) 
Described from five females and one male preserved in alcohol. Females 
14 to 20 mm. long and from 0,6 to 0,8 mm. in maximum diameter. Single 
observed male 6 mm. long and 0,46 mm. in diameter. Proboscis long, cylin- 
drical; 2 mm. or more in length and from 0,2 to 0,25 mm.in diameter; armed 
with 12 (in one instance 14) longitudinal rows of about 24 hooks each. Hooks 
on ventral surface (Fig. 4) much longer and heavier than corresponding hooks 
on dorsal surface (Fig. 3). Hooks in adjacent rows alternating except at the 
extreme base of proboscis where the basal hooks of all rows occur at approxim- 
ately the same level thus forming a single circle of 12 hooks, each about 
89 wv. long. 
Comparison of hook lengths on ventral and dorsal surfaces of proboscis of Rhad. selkirki 
(hooks are numbered from base toward tip of proboscis. Lengths are in y). 
I 3 4 5 6 7 8 9/10 TI) 52290 23 Senseo 
Ventral row 89 83 89 94 94 94 94 94 89 89 89 94 94 94 83 83 
Dorsaltow 89 253 1.053..0.53.n-.00 +,00° ..60. 65 . 65: 65:6 65: 271 7s a7 
In preserved specimens proboscis protrudes toward ventral side of anterior 
extremity at almost a right angle. Posterior region of body curved so that 
dorsal surface lies on concave rather than the more usual position on convex 
surface of body (Fig. 1). 
Proboscis receptacle 2,5; to 3,8 mm. long, double walled, with the retractors 
of the proboscis receptacle emerging from the posterior margin. 
Anterior region of body-proper provided with spines which are grouped 
into two fields. The spines at the anterior extremity of the body-proper form 
an irregular collar, the individual spines of which measure form 41 to 88 w. 
Immediately posterior to this collar is a region entirely devoid of spines. This 
in turn is followed by an area bearing conspicuous spines (Fig. 2). In some 
individuals spines of this region attain a length of 115 py. though they more 
frequently measure from 45 to 95 w. 
About 1,5 mm. from the anterior extremity of the body-proper there is 
