322 Miss H. Eichardson on the Isopods of the 



Family XI. Asellidse. 



24. AsELLUSj Geoffrey. 



Dactyli of last six pairs of pereiopoda uniunguiculate. 

 Lateral margins of segments produced. Eyes distinct, lateral. 

 Mandibles strong, with a three-jointed palp. Head without 

 rostrum. 



C6. Asellus tomalensis, Harford. 



Asellus tonvdensis, Harford, Proc. Cal. Acad. Sci. vii. 1877, pt. i. 

 pp. 54, 55. 



Ilah. Tomales Bay, California. 



Family XII. JauiridaB. 



Analytical Key to the Genera o/ Janiridte. 



a* Eyes dorsal. Antennge of first pair well developed, 

 with multiarticulate flagellum. Antennse of second 

 pair long, with multiarticulate flagellum, peduncular 

 joints not dilated. Mandibles with a three-jointed 

 palp and with cutting-part separated from molar part 

 by a deep incision. 

 b Head without any true rostrum. First pair of 

 antennse extremely small, with flagellum rudi- 

 mentary. Second pair of antennas of moderate 

 length, without any distinctly squatniform append- 

 age. First pair of legs not prehensile. Uropoda 

 extremely small, branches very short, nodiform . . 25. Jcc7'a. 

 v. Head with prominent rostral projection, or with a 

 comparatively small rostrum, or without rostrum. 

 First pair of antennae well developed; flagellum 

 multiarticulate. Second pair of antennae very much 

 elongated, with a well-marked scale-like appendage 

 outside of third joint. First pair of legs prehensile, 

 carpus large, subfusiform, and edged inside with 

 spines ; propodus narrow, linear, and very movably 

 articulated to carpus, so as to admit of being bent 

 in against it. Uropoda largely developed, with 

 branches slightly unequal. 

 c. Head with lateral parts produced to very promi- 

 nent acute lappets. Segments of thorax with 

 lateral parts laciniate and produced. Caudal 

 segment forming on each side, at the end, a tri- 

 angular expansion 20. lanthe, 



c'. Head with lateral parts not produced into lappets. 

 Segments of thorax with lateral parts not pro- 

 duced, not laciniate. Caudal segment rounded, 

 not expanded laterally 27. Janira. 



* Id. pts. 5, 6, pp. 98-100, 103, 104. 



