10 PEOCEEDINGS OP THE NATIOl^AL MUSEUM vol.72 



has but little in common. Aside from their widely separated ranges 

 Scyphacella has large eyes with numerous ocelli, small lateral lobes 

 and slender antennae. The mouth parts also seem to present a series 

 of differences, but unfortunately they are so schematically repro- 

 duced by Richardson that no detailed conclusions can be drawn. 



It thus appears that no near relative of Detonella papiUicornis 

 is known from the northern hemisphere. It seems, however, to be 

 probable that upon closer investigation, other species of Detonella 

 or related genera will eventually be found on the northern shores 

 of the Pacific. 



DETONELLA PAPILLICORNIS (Richardson) 



1904 Trichordscus papiUicornis Richardson, Proc. U. S. Nat. Mus., vol. 27, 

 p. 670, figs. 18-22. 



1905 Tri€honiscus papiUicornis Richaedson, Bull. No. 54, U. S. Nat. Mus., 

 p. 695, figs. 734r-738. 



Lacalities. — Seldovia, Cook Inlet, Alaska (Harriman Alaska Ex- 

 pedition), a single specimen found on the beach, type. United States 

 National Museum, Catalogue No. 28772 (Richardson, 1905, p. 698) ; 

 Bering Island, 1897, 2 males, 2 females (G. S. Barrett-Hamilton, 

 collector), United States National Museum, Catalogue No. 43645. 



Description. — Length of male, 3 mm. ; of female, 3.8 mm. 



Body narrow, oblong, nearly three times as long as broad, dorsal 

 surface rather strongly convex, covered with transverse rows of 

 rounded tubercles. 



Head with triangularly produced, broadly rounded median lobe. 

 Lateral lobes large, directed somewhat downwards, roundish, rec- 

 tangular. From near the center of the dorsal surface of the head at 

 each side a row of large tubercles runs outwards and backwards 

 to the posterior margin; in the center between these rows there are 

 three smaller tubercles, and a row of small tubercles follows the 

 posterior border. The front margin of the median lobe is well 

 marked by two slightly S-shaped ridges meeting at the apex of the 

 lobe. Laterally from these ridges at each side a strong elongated 

 tubercle is to be found, forming a transition from the median lobe 

 to the lateral one. 



Eyes small but distinct and prominent, black, composed of about 

 six ocelli, oblong, and situated on the lateral margins at the base of 

 the lateral lobes. 



Antennulae (fig. 3 a-h) with the basal joint large and broad, 

 second joint as long as the first but much slenderer and gradually 

 tapering, terminal joint very small, rounded, carrying three sensory 

 filaments {Leydigsche Organe)^ the longest of which are more than 

 twice as long as the terminal joint. At the extremity of the second 

 joint are two long biarticulate setae, the basal joint of which is very 

 short and at least one of which ends in four extremely delicate hairs. 



