151 



narrow, 7-articulate. Posterior antennae pronouncedly prehensile, being armed 

 at the tip with 2 or 3 curved claws. Maxillae with the terminal lappet much 

 produced and densely hairy on both edges; palp forming a small bi or tri- 

 setose lobe turning backwards. Anterior maxillipeds with the apical lash long 

 and slender. Posterior maxillipeds in female short and stout, 3-articulate, and 

 almost naked, last joint conically produced; those in male well developed, 

 subcheliform, dactylus very slender and more or less strongly curved in the 

 middle. Natatory legs with the raini comparatively broad and nearly equal- 

 sized in the 3 anterior pairs; inner ramus of 4th pair however somewhat 

 reduced in size, and composed of only 2 joints, the distal one provided with 

 2 unequal spines on the tip. Last pair of legs with the free joint compara- 

 tively small, bisetose. Ovisacs in female very large. 



Remarks. This genus was established by Thorell as early as the year 

 1860, to include 4 species found by him in the branchial cavity of various 

 Ascidians. I have been enabled to identify all these species, and they will be 

 here described and figured in detail, together with 4 additional forms, making 

 in all no less than 8 different species belonging to the Norwegian Fauna. In 

 spite of this considerable number of species, the genus is here taken in a 

 much more restricted sense than is done by most other authors, who refer to 

 it forms which in my opinion evidently are not congeneric. Some of these 

 aberrant forms have certainly been separated by Glaus and Canu as types of 

 nearly-allied genera; but I think that this generic separation must be car- 

 ried still further. The peculiar rudimentary condition of the caudal setae 

 observed in the species described by Thorell cannot however properly be 

 regarded as a character of generic value, but is evidently due to the seden- 

 tary habits of these forms within the branchial cavity of Ascidians. In 3 of 

 the species described below, these setae, as shown by the figures, are quite 

 normally developed; and it is very likely that the said species do not at all 

 have their abode within Ascidians, but are true ecto-parasites, as has indeed 

 been proved as regards at least one of them (L. agilis). 



79. Lichomolgus albens, Thorell. 



(PI. LXXXIII). 



Licliornolgns albens, Thorell, Bidrag til Kannedomen om Krustacecr som lefva i Artcr af slagtet 



Ascidia, p. 69, PI. X, XI, XII: 15. 



Specific Characters Female. Body moderately slender, with the 

 anterior division rather dilated in front and pronouncedly applanated. Cepha- 

 lic segment broadly expanded, and exhibiting in its posterior part dorsally a 



