536 



where, in some places, it is rather aliuiidant, for instance at Be^jan, in the 

 outer part of that fjord. 



Distrihution. — Arctic Ocean : Greenland (Hansen), Spitsbergen (Goes), 

 Bohuslan (Malm). 



Gen 12 Idunella, G. O, Sars, n. 



Form of body about as in LiUjiboiyia. Urosome without any dor.sal 

 projections. Eyes imperfectly developed. Antennae snberiual in length, the 

 superior ones with a well-developed accessory appendage. Oral ))arts 

 reseml)ling tliose in LiUjehorrjia, except that the mandibular palps are much 

 more full_y developed, with the terminal joint elongated and falciform, and 

 that the palps of the maxillipeds are smaller. Gnathopoda in female subequal, 

 with tlie c^arpus Init slightly produced below, and the propodos much ex])anded 

 distally, dactylus smooth. Anterior gnathopoda in male much larger tlnin 

 the posterior, and peculiarly modified, lieing conspicuously forcipate, witli 

 the palm of the jJi'opodos deeply concave, and produced below to an acute 

 projection, against which the strongly curved dactylus impinges when closed. 

 Pereiopoda nearly as in Lilljcborgia. Last pair of uropoda with tlie outer 

 ramus distinctly biarticulate. Telson rather large and deeply cleft. 



lleitiarls. — This new genus is founded upon the form described at 

 an earlier date by the autlior as LUljehorgia aqvicornis. On a closer examiim- 

 tion of this form, I have found it to diflPer in several points so very markedly 

 from tlie other species of Lillieborgia, as more ])roperly to be regarded as the 

 type of a separate, thougli closely allied genus, for which I have proposed the 

 above name, being the diminutive form of Iduiia. Besides in the subequal 

 antennae, and in the remarkable structure of the gnathopoda in the two sexes, 

 it differs in the much fuller development of the mandibular palps, whereas 

 the \rd\\)s of the maxillipeds are not nearly so strong as in the genus 

 LiUjehoiyid: it further differs in the outer ramus of the last jiair of uropoda 

 being distinctly biarticulate. The genus comprises as yet but a single species, 

 to be described below. 



