O N I S C I D E A. 725 



and Trichoniscus, as distinct genera, but as subgenera of the genus 

 Oniscus. Deto, in having the flagellum so remarkably short, diverges 

 more from the Oniscus type ; and Platyarthrus, in the broad, flattened 

 fifth joint of the antennae is also sufficiently distinct ; but we make 

 this flattened joint the characteristic of the genus, without adding to 

 it the number of joints in the flagellum, except so far as to say, that 

 the number is small (one to three or four), as in Oniscus. 



PORCELLIO GEMMULATUS. 



Abdomen thorace non subito angustius. Capitis processus antero-lateralis 

 valde prominens, subtruncatus, fronte triangulatus. Segmenta thoracis 

 abdominisve gramdis ornata, granulis juxta marginem segmentorum 

 posticum bene seriatis, alioque partim seriatis ; segmenta abdominis 

 3tio 4to htoque lateribus expansa et salientia, ultimum triangulatum et 

 subacutum, latere excavatum, Jatitudine basali vix longius, basi sty- 

 lorum vix longius ramos internos non, superans. Antennas subtiliter 

 hirsutce, articulo tertio spina non armato, fiagello biarticulato paulo 

 breviore quam articulus precedens. 



Abdomen not abruptly narrower than thorax ; anterolateral process 

 of the head very prominent, subtruncate, front triangular. Seg- 

 ments of both thorax and abdomen with granules, a row along 

 posterior margin of each, and others partly seriate ; third, fourth, 

 and fifth of abdomen laterally expanded and salient; last segment 

 triangular and subacute, hardly longer than breadth at base, but 

 slightly longer than base of caudal stylets, and hardly projecting as 

 far as apex of inner branch of the stylets. Antennae very finely 

 hirsute, third joint without a spine, two-jointed flagellum shorter 

 than preceding joint. 



Plate 47, fig. 7 a, animal, enlarged four diameters; b, extremity of 

 antenna, much more enlarged ; c, apex still more enlarged ; d, leg of 

 second pair, enlarged; e,/, g, spines of under surface of same leg, from 

 fourth ioint. 



California, near San Francisco ; also, Pugefs Sound. 



182 



