MEGARTHKUM. 175 



paratively small ; branches of palp moderately elongate and 

 subequal, lower branch armed with two (or three) peculiarly 

 strong spines in addition to several seise. Other oral parts as in 

 Dactt/lopusia. First pair of thoracic feet with the three- 

 jointed outer ramus considerably shorter than the inner ; 

 inner ramus composed of two joints, the first joint longer 

 than the entire outer ramus, and greatly dilated at the base 

 but tapering to the distal end, second joint very short and 

 arined at the apex with one strong but moderately short claw 

 and an elongated seta. The second to the fourth pairs of 

 feet somewhat similar to the same pairs in Dactylopusia, 

 in which both rami are distinctly three-jointed, but the 

 middle joint of the inner ramus has only one seta on the 

 inner margin. Fifth pair large and foliaceous; the basal or 

 primary joint forms a broad quadrangular plate, with a deep 

 notch near the middle of the outer edge, in which the small 

 secondary joint is articulated (see fig. 4, PI. XX.). 



Male unknown. 



This genus approaches Dactylopodella, G. 0. Sars, but 

 differs distinctly in some important anatomical details, as in 

 the character of the mandible and mandible-palp, in the 

 structure of the inner rami of the first and second pairs of 

 thoracic feet, and in the form of the fifth pair. Three 

 species belong to this genus, one of which is described 

 below. 



MEGARTHRUM PURPUROCINCTUM, Norman & T. Scott. (Pis. X. 

 fig. 17; XII. fig. 10; XIII. fig. 10; XIV. fig. 9; XVIII. 

 fig. 6; XIX. fig. 1; XX. fig^ 4, 5.) 



1905. Dactylopusia pur/mrocincta, Norman & Scott, Ann. & Ma 01 . 

 Nat. Hist. ser. 7, vol. xv. p. 295. 



Description of the female. Body depressed and expanded 

 as in Dactylopodella fava (Clausj ; length about '5 mm. 

 (^ - of an inch). Seen from above the cephalic segment is 

 broadly and evenly rounded in front and is about as long as 

 the remaining thoracic segments. The three segments 

 immediately posterior to the cephalon are of a dark purple- 

 brown colour, but the colour of the rest of the body is lio-ht 

 yellow (PL XIX. fig. 1). 



The antennules are short, moderately stout, and apparently 

 only seven-jointed (PL XIII. fig. 10) ; the first and second 

 joints, which are robust, are longer than the others, while 

 the penultimate joint is small ; the formula shows approxi- 

 mately the lengths of the various joints : 



Proportional lengths of the joints .... 34.13.8.8.5.3.7 

 Numbers of the joints 1 2 3 4 5 6 7 



