2IÓ 



large rounded cephalic segment, by the absence of a rostrum, by the greatly developed mandible 

 jDalp, and by the structure of the first pair of feet. The joints of the basiopodite of the first 

 pair of feet are very broad and flattened. The exopodite and endopodite are three-jointed. 

 The exopodite is comparatively short and narrow. The endopodite is longer than the exopodite. 

 The first joint is very large and wide. 



One species belonging to this genus was represented in the material collected by the 

 'Siboga' in the Malay Archipelago. 



i. Idomene laticaudata (Thompson and Scott). 



Dactylopusia la li eau data Thompson & Scott, 1903, p. 271, pi. XI, figs. 1 — 8. 



Two females belonging to this species were found in the washings from dredged inver- 

 tebrata collected at Station 273, from a depth of 13 metres. 



The species was originally described as a Dactylopusia, but it undoubtedly belongs to 

 the genus Idomene described by Philippi in 1843, as suggested by Professor G. O. Sars. 

 The very short flattened spines on the apex of the proximal joint of the fifth pair of feet 

 readily separate this species from Idomene forfieata Philippi. 



This Idomene has only previously been recorded from Ceylon. 



Genus Tydemanella nov. 



The body is much dilated and slightly depressed in front, considerably attenuated 

 behind. The cephalic segment is large and expanded, and provided with a well developed 

 rostrum. The antennules are eight-jointed. The exopodite of the antennae is composed of a 

 single joint. The mandibles, maxillae and maxillipedes are of the normal type of the family. 

 The exopodites of the four pairs of feet are three-jointed. The endopodite of the first pair of 

 feet is two-jointed and is longer than the exopodite. The first joint is long and moderately 

 broad. The second joint is short. The endopodites of the second, third and fourth pairs of feet 

 are three-jointed. The fifth pair is composed of two rather wide joints. 



This genus is closely related to Dactylopodella G. O. Sars, but it can readily be separated 

 by the long slender eight-jointed antennules, and by the one-jointed exopodite of the antennae. 



One species belonging to this genus was represented in the material collected by the 

 'Siboga' in the Malay Archipelago. 



The genus is named in compliment to Lieutenant G. F. Tydeman, the Commancler of 

 H.M.S. 'Siboga' when the investigations were carried out in the Malay Archipelago. 



1. Tydemanella typiea nov. sp. Plate LXIII, figs. 15 — 24. 



Female — length 1,15 mm. 



Seen from above, the body appears rather long and is pyriform in shape. The cephalic 

 segment is large and broad. It is slightly longer than the combined length of the thoracic 

 segments. The rostrum is large and well developed. 



216 



