165 



points rather materially from the type of that genus. Thus, the eyes, when pre- 

 sent, are not aggregate, but simple, each consisting, as in the genus Haploph- 

 Ihidmux, of but a single visual element. Moreover, the number of penicils 

 attached behind the cutting part of the mandibles is different, and the niaxillipeds 

 are less produced. Finally, the legs are of more uniform length, and the struc- 

 ture of the 2 anterior pairs of pleopoda in the male is rather peculiar. In addition 

 to the species described below, the Trichonlscus J^'t/dit/i of \Yeber undoubtedly 

 belongs to this genus, and perhaps also the Tnchuiiiwu* cavernicola of Budde-Lund. 



Triehoniseoides albidus, (B.-Lund). 



(PI. LXXIII, fig. 2.) 

 Trichonisciis albidns, Budde-Lund, Prosp. gen. spec. Crust, terresfcr., p. 9. 



ClinriK-tcrs. Body narrow oblong, 3 times as long as it is broad. 

 and strongly convex, almost semicylindric, dorsal face rough owing to minute tu- 

 bercles arranged, on each of the segments of mesosome, in 2 or 3 transversal 

 rows, each of the tubercles being tipped by a small hair. Cephalon transversely oval, 

 with the lateral lobes minute, rounded and slightly denticulate, front evenly ar- 

 cnate. Lateral parts of mesosome edged with small appressed spikes, the 4 an- 

 terior pairs but very slightly prominent, the 3 posterior pairs produced to re- 

 curved acute points. Metasome occupying about J / 4 of the length of the body, 

 and much narrower than the mesosome, with the epimeral plates small and ail- 

 pressed ; terminal expansion of last segment narrowly truncated. Eyes distinct, 

 but extremely small, circular, consisting each of a single corneal body with under- 

 lying reddish pigment. Antennulse with the terminal joint but little longer than 

 the 2nd, and carrying 4 sensory filaments, basal joint rather large, exceeding in 

 length the other 2 combined. Antenna? scarcely exceeding '/4 of the length of 

 the body, flagellum composed of 4 articulations. Last pair of legs in male with 

 the meral joint produced at the base to a comparatively small dentiform promi- 

 nence, last joint in both sexes densely ciliated outside. First pair of pleopoda in 

 male with the opercular plate large, quadrangular, abruptly contracted at the tip, 

 and prolonged to a setiform ciliated lash curved outwards and accompanied in- 

 side by another much smaller seta; inner plate comparatively small, with a 

 long, posteriorly pointing ciliated seta springing from the inner corner. Inner 

 ramus of 2nd pair distinctly Inarticulate, terminal joint forming a narrow folded 

 plate terminating in an acute point. Uropoda with the inner ramus a little 

 shorter and much narrower than the outer, apical spine exceeding half the 

 length of the ramus. Body, in the living state of the animal, semipellucid, of a 



