CUMACEA PEOM THE COPENHAGEN MUSEUM. 25 



specimen described above as H. longicornis, and it also approaches that species in the 

 elongate peduncle of the antennule. It is distinguished, however, not only by the 

 marked antero-lateral teeth, but by the shorter first legs. 

 Occurrence. — " Penang, Didrichsen." Copenhagen Museum. 



Genus Ztgosiphon, gen. nov. 



Carapace with double pseudorostral projection and two widely separated and very 

 long branchial siphons. Five leg-bearing somites distinct. Basis of third maxillipeds 

 produced dis tally. Only the first pair of perseopods with exopods. Endopod of 

 uropods of two segments, distal segment short. 



Type species Z. mortensem , sp. n. 



This new genus is distinguished chiefly by the remarkable development of the 

 branchial siphons and their separation from one another, and by the correlated 

 peculiarities in the shape of the anterior part of the carapace. In other respects it 

 does not difier very strikingly from some of the existing genera of Bodotriidge. 



Zygosiphon moktenseni, sp. n. (Plate VII. figs. 1-19.) 



Description of adult Female. — Total length 2'67 mm. 



The carapace is about two-sevenths of the total length, somewhat compressed, its 

 vertical height two-thirds of its length. The dorsal edge is slightly arched and rises 

 in a rounded transverse ridge posteriorly. Viewed from above, the carapace is rather 

 broader in front than behind, with nearly straight or, in ovigerous specimens, concave 

 sides. In front it is squarely truncate, having at the corners, which are somewhat 

 produced, the two widely separated branchial orifices from which are protruded the 

 very long branchial siphons directed obliquely upwards and outwards. There are thus 

 two short pseudorostral processes instead of one. Seen from the side they are obliquely 

 truncated, with the lower corner projecting in front of the upper. The lateral pseudo- 

 rostral plates meet for a short distance in front of the ocular lobe. The antennal 

 notch is rounded and widely open, and the antennal tooth is triangular and rather 

 prominent. The ocular lobe is very broad, with its anterior margin notched so as to 

 indicate a division into two parts. It contains two separate masses of ocular pigment, 

 but there are no distinct corneal lenses. On each side of the carapace is a lozenge- 

 shaped depression bounded by indistinctly marked ridges. From its anterior corner a 

 ridge runs forward on to the side of the pseudorostrum, and above this the surface is 

 slightly excavated on each side of the middle line. 



The first leg-bearing somite is completely exposed, and, like the second, is nearly 

 equal in height to the posterior part of the carapace. The three posterior somites are 

 much lower and diminish rapidly in width posteriorly. In ovigerous specimens the 

 greatest width of the body is reached at the second free somite. 



VOL, xviii. — PART I. No. 4. — August, 1907. e 



