56 University of California Puhlications. [Zoology 



Genus Gaetanus Giesbrecht. 



Gaetanus, Giesbrecht ('92), p. 53, 219; ('98), p. 32. 



Female : Rostrum short, with one point. The front of the 

 head on the dorsal surface bears a median spine (PI. 9, figs. 3, 4, 

 5). Cephalothorax and abdomen symmetrical, each of four seg- 

 ments, the last thoracic segment lengthened on each side into a 

 long spine (PI. 10, fig. 24). Anterior antennae 23- or 24- jointed; 

 inner ramus of the posterior antennae about four-fifths as long 

 as the outer ramus. Outer ramus of the first foot 2- or 3- jointed, 

 inner ramus of the second foot 2-jointed. Inner border of the 

 first basal of the fourth foot provided usually with lamellae or 

 spines at the distal portion instead of bristles (PL 13, fig. 76). 



Male : Head with the spine which is characteristic of the 

 genus. Abdomen of five segments. Anterior antennae 22-jointed ; 

 mouth parts retrograded. Fifth feet much as in Gaidius; outer 

 ramus of each foot 3-jointed, inner rami rudimentary and 1- 

 jointed. The inner ramus of the left foot is slender and rod- 

 shaped, that of the right foot heavy and club-shaped (PI. 14, fig. 

 90). 



Gaetanus brevicornis n. sp. 



PI. 9, fig. 4; i>L 12, fig. 55. 



Female: Head (PI. 9, fig. 4) with a spine and quite similar 

 to G. armiger Giesbrecht, but heavier. Anterior antennae extend 

 about to the end of the furca. The second joint of the outer ra- 

 mus of the posterior antenna has a small process, as in G.armiger. 

 The lamellar process on the first basal of the posterior maxilliped 

 (PL 12, fig. 55) is more prominent than in G. miles. The outer 

 ramus of the first foot is indistinctly 2-jointed, first basal of 

 fourth foot with a row of delicate hairs, quite different from the 

 tube-like bristles of G. miles, and not so heavy even .as in G. ar- 

 miger. 



Length : 4.3 mm. 



Coloration : Opaque and without pigment. 



Occurrence: One female, Coll. 1030. Type in the collection 

 of the University of California. 



