REPORT ON THE SCHIZOPODA. 177 



broadly truncate at the apex. The lateral edges are in the outer half finely denticulate, 

 and the apical edge juts forth in the middle as a short dentifoi-ni projection, on (ntlier 

 side of which are affixed five strong spines (see fig. 9). 



The uropoda (see fig. 8) have the inner plates of about tlie same length as the 

 telson and narrowly lanceolate in form, whereas the outer plates are considerably larger, 

 and clearly distinguished by the outer linguiforra part being marked off" from the plate 

 by a very distinct articulation, a feature not observed in any other known form of 

 Mysidans. The outer edge of the plate is quite smooth, and terminates as a distinctly 

 projecting corner bearing a short spine, whereas the terminal articulation and also the 

 whole inner edge of the plate is fringed with a dense row of ciliate setae. 



Habitat. — The above described specimen was taken in the Tropical Atlantic, at a 

 very considerable depth. Locality:. Station 104, August 23, 1873; lat. 2' 25' N., 

 long. 20° 1' W.; depth, 2500 fathoms ; Globigerina ooze ; bottom temperature, 36°-6. 



Genus 2. Boreomysis, G. 0. Sars, 1869. 

 Boreomysis, G. O. Sars, UndersogeLser over Christianiafjordens Dybvandsfauna. 



Generic Characters. — Carapace rather large, covering most of trunk, antero-lateral 

 comers produced, lobiform. Tail slender, cylindrical, with last segment longest. 

 Antennular peduncle comparatively robust, with male appendage very short, tuber- 

 culiform ; outer flagellum more or less distinctly expanded at base. Anteniial scale 

 elongate, sublinear ; outer edge smooth, terminating in a dentiform projection. Last 

 joint of mandibular palp narrowly oblong. Second pair of maxillae with inner expan- 

 sion of basal part very broad, terminal joint oval, with some of the bristles recurved. 

 Gnathopoda elongate, with terminal joint very mol)ile and densely hirsute. Legs 

 rather slender, subequal, with propodal joint subdivided into two or three articulations, 

 terminal joint unguiform. Marsupial pouch in female composed of seven pairs of 

 incubatory lamellae. Caudal limbs in male all natatory, with very elongate branches. 

 Telson large, deeply incised at apex. Outer plate of uropoda with a ledge-like pro- 

 minence in front of the middle exteriorly, bearing two small denticles. Auditory 

 apparatus at base of inner plate rudimentary. 



Remarks. — This genus is distinguished from most other Mysidans bv havini'- the 

 marsupial pouch of the female composed of seven pairs of incubatory lamellae. In this 

 character it agrees only with the preceding genus, from which, however, it may be 

 easily recognised by a deviating structure of the antennular peduncle, the' antennal 

 scale, and the caudal fan, besides the male sexual characters, which in the present 

 genus are quite normal, whereas in the former they are very peculiar and 

 anomalous. 



The typical species is Boreomysis arctica (Kroyer), first met with in the Arctic Sea, 



(ZOOL. CHALL. EXP. PART xxxvu. — 188.5.) Oo 23 



