lO 



styliform joint {G. parvus n. sp., PI. VIII, figs. 3^'— 3'«); taking the dose relationship between 

 the species into consideration the features pointed out show that sometimes the degree of the ol 

 reduction of the pleopods, e.xcepting the characteristic ramus, is of sUght importance and ought 

 not to be used as the sole character for new genera. — In Pscudanchialina n. gen. we proceed 

 a step further: third pair of pleopods are developed essentially as in Gastrosaccus bengaletisis 

 n. gen., while not only fourth and fifth pairs but even first pair consist of a single joint and 

 the second pair are still more reduced than in any species of Gastrosaccus. 



In the large subfamily Mysinse the pleopods show most different degree of development, 

 but in the great majority of genera one of the rami of fourth pair and most frequently the 

 exopod is especially developed, slightly to very much elongated or adorned with peculiar setae, 

 while the rami of third and second pairs are either well developed and normal or less or more 

 reduced. — In the tribe Erythropini the four posterior pairs are well developed; in Erythrops 

 G. O. S. and P seudo^nvia G. O. S. the fourth pair have — according to Sars — the endopod 

 slightly longer than the exopod, with some of its most distal setae considerably stronger than 

 usual; in Amblyops abbreviata G. O. S. it is the exopod which shows a similar development. 

 In the majority of the other genera belonging to this tribe the pleopods have not been specially 

 examined as to such minute details. In Holmesiella Ortm., which according to the shape of 

 the antennal squama and the very oblique articulation on sixth joint of the thoracic legs ought 

 to be removed from the Leptomysis-gxow'^ (where it was placed by Ortmann) to the Erythropini, 

 the endopod of fourth pair is very elongated, about twice as long as the normal exopod. It 

 may be added that a special development of the endopod of fourth pair is only found in the 

 Erythropini, not in any genus of the other tribes of the subfamily Mysinae, but, as already 

 stated, at least in one case the exopod instead of the endopod is a little more developed, and 

 sometimes both rami are quite normal. 



In the tribe Leptomysini the exopod of first pair and both rami of the other pairs are 



well developed in all genera (viz. Mysidopsis G. O. S., Mysideis G. O. S., Leptoinysis G. O. S., 



Pseudoinysis G. O. S., BatJiyniysis Tatt., Uromysis n. gen.) excepting Mysidetes Holt & Tatt. ^), 



but the exopod of fourth pair is either slightly or considerably longer than the endopod, as a 



rule with its most distal setje peculiarly developed. In Mysidetes all ple.opoda are rudimentary. 



In the tribe Mysinae {Stilomysis Norm, included) the fourth pair have the endopod 



reduced and the exopod very or extremely elongated, while first and second pairs always, fifth 



pair frequently and in one genus {Anisomysis n. gen.) even third pair are so reduced that they 



may be considered rudimentary. A single exception from the rule as to the development of 



fourth pair is the genus Hetcromysis Smith, in which all pairs are rudimentary as in the female. 



Uropods. — In the Petalophthalmidae the distal part of the exopod is marked off 



by an articulation, and the same feature is found in the majority of the Lophogastrida. In 



Rhopalophthahiins Illig both rami (PI. VII, fig. \c) are divided by a very conspicuous articulation 



beyond the middle. In the Siriellinae the exopod shows a feebly developed distal articulation, and 



at least the most distal part of the outer margin of the proximal joint is provided with spines; 



l) The male is unknown in the genus Metamysiddla Illig, which probably belongs to this tribe. 



