304 DR. H. J. HANSEN ON THE [NoV. 29, 



nearly as long as the maxillulee, rather slender ; the lobe from 

 the second joint oblong, as long as the two lobes from the third 

 joint. Maxillipeds (fig. 3 h) large ; second joint — the lobe not 

 taken into consideration — veiy large, more than twice as long as 

 broad, its lobe, which is marked oW by a transverse suture, is 

 large, longer than broad, with several small hooks at the inner 

 margin, while the distal margin is cut off and fvirnished with 

 several short setfe, some of which are very broad, scale-like ; fourth 

 and fifth joints rather expanded ; the two distal joints slender. 

 Epipod very long, about three times longer than broad. Basal 

 joint in the adult female without any leaflet directed into the 

 marsupium. 



Thorax shaped nearly as in lanira ; anterior lateral angle of 

 first segment always produced into a triangular, acute, flat 

 pi'ocess directed forward*. First pair of legs terminates in a 

 prehensile hand, the sixth joint being large, compressed, with 

 the palmar margin armed with processes or remarkable spines or 

 setfe, while the seventh joint togethei' with its short terminal 

 claw is slender and claw-shaped ; this hand shows sometimes 

 rather little, but often a highly developed, sexual difference, being 

 frequently not only much larger in the adult male than in the 

 female, but of quite another shape. The six other pairs of legs 

 essentially as in lanira ; seventh joint terminates in a claw, 

 beneath which a spine of the same size is seen. Marsupial 

 la,mell£e four pairs, proceeding from first to fourth pair of legs. 



Abdomen essentially as in lanira ; two rudimentary segments 

 are observed in front of the large abdominal shield ; the latter 

 has at the end of each lateral margin a small notch, the outer 

 margin of which is formed by a shai'p triangular tooth. 



Pleopoda are exceedingly chaiacteristic t. In both sexes the 

 third pair is only to a very small extent (PI. XIX. fig. 1 d) covered 

 by the first pair (in the female) or the two anterior pairs (in the 

 male) ; its sympod is rather small, quadrangular (PI. XX. figs. 2 i 

 and 2 n) ; the two-jointed exopod is exceedingly large, scarcely 

 respiratory, and covers the respiratory endopod, which is unjointed 

 and several times smaller ; the inner margin of each exopod is 

 straight, and the two exopods touch each other along the mesial 

 line, constituting together a kind of operculum which covers the 

 lower surface of abdomen, with the exception of a moderately broad 

 margin at the sides and behind, and a small portion in front 

 occupied by the anterior pleopoda. In the female the pleopoda 

 of the first pair are completely fused (PI. XX. fig. 2 m ; PI. XXI, 

 fig. 2 i), constituting a subtriangular more or less oblong operculum, 

 which is at least three times smaller than an exopod of the third 



* According to Haswell this process is wanting in 8. inerme Hasw., but in the 

 sequel it is shown that this species probably does not belong to the genus 

 Stenetrium. . 



t In Section V. of this paper the comparative morphology of the pleopoda in the 

 Asellota is discussed ; in this account of Stenetrium and in Sections III. and IV. 

 the structure of the pleopoda is described and the interpretations applied without 

 explanations. 



