0. SAES. 



[No. 7. 



edge in adult females quite smooth, ventral edges of valves with 

 a double row of slender spines. Eye rather large; ocellus very 

 small, quadrangular. Antennulae strapshaped, slightly curved 

 with about 6 notches along the anterior edge, each with a tuft of 

 very minute hair; a similar tuft behind the apical sensory fila- 

 ments; those of male much larger, anteriorly with a ciliated 

 seta at some distance from the base. Antennae about as in M. 

 Jaticornis. Tail with the outer part slightly produced and 

 rounded, dorsal edge sinuated beyond the middle, evenly curved 

 proximally and armed with a single row of strong denticles. 

 Colour pale yellowish. Length of adult female 0.66 mm; of male 

 0.31 mm. 



Remarks. — This form must, I feel sure, be the one that 

 King has noticed under the above name. It is however very 

 insufficiently described by that author, and the characters on 

 which he bases the species, apply equally well to the other 

 known species. The resemblance to the European form, M. laii- 

 cornh- (Jurine), is indeed very great, and not till after a most 

 minute examination did I succeed in determining a few distinctive 

 characters. Of these the smooth dorsal edge of the carapace 

 may take the first place. 



Description. — The length of the adult female reaches 

 0.66 mm. and the species is thus somewhat larger than as a rule 

 the European species M. laticornis, which undoubtedly is that 

 nearest related to the present form. 



The carapace, as seen laterally (PI. 3, fig. 1), is rounded 

 oval, very little longer than broad, and tapers somewhat poste- 

 riorly. The dorsal edge is but slightly arched in the anterior 

 part; posteriorly, however, it bends downward with a rather 

 sharp curve and terminates in a very slight angular projection, 

 located about in the longitudinal axis of the carapace. The 

 valves are comparatively small, and hence a considerable part 

 of the tail remains constantly uncovered, as also the tip oi 

 the anterior legs. Their anterior edges are nearly straight and 

 do not wholly cover the mandibles; they join the inferior edges 

 with a very sharp, almost angular curve. The latter edges are 



