59 



Pseudanchialina n. gen 



This genus is established on Anchialus pusillusG. O. Sars and Clilamydopleon inermc Mig, 

 both hitherto somewhat imperfectly known. The genus may be characterized in the following way. 



Description. — Animals very small, with the cephalothorax somewhat clumsy. Carapace 

 produced into a well-sized frontal plate ; posteriorly it covers almost the whole cephalothorax 

 or sometimes even the front part of the first abdominal segment, and its liind margin is 

 proportionately feebly concave. Eyes well developed. Antennulce with the peduncle considerably 

 thicker in the male than in the female ; the rudimentary male lobe with a small bundie of 

 hairs. Antennal squama somewhat small, increasing much in breadth from the base to the end, 

 with the outer margin naked and slightly concave; the marginal denticle unusually long; the 

 terminal lobe with a transverse suture; most of the sette on the inner and the terminal margins 

 extremely long (PI. IX, fig. i d). Labrum produced anteriorly into a very long, distally slender, 

 acute process reaching not quite to the end of second joint of the mandibular palps. Left 

 mandible (PI. VIII, figs. ^a — 4/') with the cutting edge and the movable lacinia well developed; 

 behind the latter two thick sets, each projecting from a small knot; the molar tubercle well 

 developed though not broad ; the palp with the second joint about three times as long as 

 broad and moderately broad in almost its whole length; third joint not quite half as long as the 

 second. MaxillulEe normal (PI. VIII, fig. 4^); maxillae (PI. IX, fig. ie) nearly as in Gastrosaccus. 

 Maxillipeds (PI. IX, fig. \f) with first and second joint extremely broad; second joint without 

 lobe; the four following joints somewhat robust, simple; seventh joint very slender, and the 

 claw proportionately long. Gnathopods (PI. IX, fig. i^-) with the two proximal joints very broad, 

 the other joints normal, somewhat robust, the claw strong and very long. The endopods of the 

 thoracic legs are wanting in my specimens, but according to G. O. Sars they are somewhat 

 slender, with sixth joint divided into a few subjoints. The female marsupium consists of two 

 pairs of plates, first pair very small, the other extremely large. 



First abdominal segment in the female of P. inermis with the lateral wings essentially 

 as in Anchialina; in P. pusilla I have not been able to find such wings, but the material of 

 adult females is scanty and badly preserved. Sixth segment in both sexes conspicuously longer 

 than the sum of the two preceding segments (PI. IX, fig. 1 d). All pleopods in the female simple, 

 styliform. In the male first, fourth and fifth pairs of pleopods rudimentary (fig. 1 h) and styliform 

 as in the female; third pair in the main as in Gastrosaccus, but differing in having the peduncle 

 longer and the exopod proportionately shorter than in that genus; second pair essentially as in 

 some forms of Gastrosaccus, but the unjointed endopod still more reduced. Uropods (fig. 1 1) 

 somewhat slender with extremely long setse, especially on the end of the rami ; exopod not 

 longer than the endopod, its outer margin naked with a single spine a little in front of the 



and produced as a kind of plate considerably beyond the articulation with the terminal joint, covering the proximal part of the inner side 

 of this joint. Fourth and fifth pairs nearly as in G. imiicus, but their exopods are three-jointed. Uropods with 12 or 13 spines on the 

 outer margin of the exopod. Telson scarcely three times as long as broad, generally with 12 or 13, in a perhaps somewhat anomalous 

 specimen with only 10, spines aloDg each lateral margin, the two last pairs always very long, a little less or a little more than twice as 

 long as the antepenultimate pair. — Length of the males 5.4 — 6 mm., of the adult females 5.7 — 6.5 mm. 



