TANAIDACEA AND ISOPODA— TATTERSALL. 199 



Order ISOPODA. 



Sub-order ASELLOTA. 



Family PARASELLIDAE. 



Group JANIRINI. 



Hansen, 1916, in kis account of the Isopoda of the Ingolf Expedition, has expressed 

 the opinion that several genera closely allied to Janira have been founded on insufficient 

 grounds. Among these genera, lolella, Richardson ( = lantlie, Bovallius, and Tole, 

 Ortmann), is definitely relegated by Hansen to the synonymy of Janira, and he at least 

 implies that lanthopsis and lolanthe should share a similar fate. 



Vanhoffen, on the other hand, places lolella, lanthopsis and lolanthe, with four other 

 genera, in a separate family, the lolellidae, which he briefly diagnoses as " Janira-\^k& 

 forms with a more or less distinctly prominent rostrum, with notched lappets drawn 

 out at the sides of the somites, and with two or more side thorns on the abdomen." He 

 suggests briefly a revision of the genera of this family. The name lolella is applied to 

 those species In which the abdomen is produced into two long and pointed lateral 

 extremities with no clearly marked central portion, and lanthopsis is retained for those 

 species in which the lateral processes of the abdomen are pointed and separated from 

 the distinct but broadly rounded median process by deep notches. These distinctions 

 are very slight, and the case for the inclusion of both genera in the older genus Janira 

 is strengthened by the fact that one species, lanthopsis libbeyi (Ortmann), which 

 Vanhoffen includes in the genus lanthopsis, has been shown by Hansen to be a synonym 

 of Janira tricornis, Kroyer. But Hansen has himself suggested a division of the genus 

 Janira which is based on much more definite characters. He notes that the species of 

 Janira taken by the " Ingolf" Expedition fall into three groups, as follows : — 



" A. Epimeral plates developed at all thoracic segments. The plates are small, 

 never produced into long acute processes, but bifid at two or three of the 

 segments. 



" B. Epimeral plates completely wanting. 



" C. Epimeral plates developed at the three posterior segments but wanting at least 

 at second and third segments." 



These three divisions or groups of the genus Janira correspond to the genera 

 Janira (A), Ianthop)sis (B) and lolella (C) of Vanhoffen. There can be no question 

 that all the genera belong to the same family or group, and Hansen's classification is 

 the most natural one yet proposed and the one I follow here. But I think there are 

 sufiicient grounds for the retention of the three divisions of the genus Janira, indicated 

 by Hansen, as generic groups under the names Janira, lanthopsis and lolella. 



VOL. III. 2 Cr 



