IN THE NEST OF A MOIiUSC 381 



have no molar tubercle, and the 'palp' is very small, 

 indistinctly two-jointed. The limbs are nearly as in 

 Munna. The uropods are very short, two-branched, the 

 branches simple, unequal. The Norwegian species are 

 rubicundum, spinosissimum, and inerme, all instituted by 

 Sars. Beddard has added two species from Kerguelen and 

 one from Tristan da Cunha. 



Acanthomunna, Beddard, 1886, is akin to Munna, but 

 the first antennte have a long instead of a short flagellum, 

 and the limbs of the perseon have the seventh joint simple. 

 The type is Acanthom/imna proteus from New Zealand. 



Leptaspidia, Bate and Westwood, 1867, has not been 

 very fully described. The animal is said to be ' pear- 

 shaped, flattened,' but the latter epithet does not well apply 

 to the ovigerous female. The pleon is oval, entire and 

 almost acute at the apex. The limbs, except the first pair, 

 are very slender, but not very short ; they have the seventh 

 joint simple. The uropods are minute, single-jointed, 

 lateral. The first pleopods are said to ' shut together in 

 the form of a flattened pear, divided down the centre.' The 

 impression given by the figure is of a pair of valves as in 

 the tribe valvifera. This may be correct in regard to the 

 male, but in the female there is a single opercular plate, 

 slightly carinate down the centre. The type is Leptaspidia 

 hrevipes, from the Clyde, where this microscopic species 

 was first found by Mr. David Robertson in the strange 

 fibrous nests of the mollusc Lima Jiians. It has no eyes. 



NeaseUus, Beddard, 1885, is near to Pleurogonium and 

 Pa/ramunna in character, and in the articulation of the first 

 antennse below the lateral extension of the head it re- 

 calls the appearance of Leptaspidia. The first and second 

 segments of the perseon are dorsally fused in the middle ; the 

 fourth and seventh segments are narrower than their neigh- 

 bours. The type is NeaseUus Icerguelenensis (see Plate XIV.). 



Astrurus, Beddard, 1886, is much like Leptaspidia and 

 Flffwrogonium, in appearance. There appear to be traces of 

 eyes. The fingers are not bifid. The uropods are rudi- 

 mentary, yet perhaps two-jointed. The type is Astrurus 

 crucicauda from the prolific vicinity of Kerguelen. 

 28 



