31 



in reality constructed upon the very same type as in the true Lysianassidae, 



and in some of the latter, for instance Acn/o^/nnm (see PI. U, tin-. _> ,],,. 

 agreement is quite unmistakable. As to the anomalous appearance of the 



anterior gnathopoda, Dr. Bovallius has shown this to be merely due to a 

 peculiar torsion of the outer part of the leg-, whereby tin- hand becomes quite 

 inverted in the adult animal, whereas in the young these liml.s rxliil.it a tar 

 more normal appearance, nearly agreeing with that met with in the genus 

 Normnnu. (see PL 13, fig. 1). On the other hand the post, .rim' -nathopoda 

 are indistinguishable, both as to form and structure, from those in the tvpical 

 Lysianassidse. Finally the urosome, which in Boeck's opinion, is evidently 

 Hyperiidean in character, essentially differs by being divided [ n to .". distinct 

 segments and by the last pair of uropoda having a distinct terminal joint, as 

 is the case in the greater part of the typical Gammaridea. Moreover, the. 

 whole exterior habitus and the structure of both the antenna' and the lee-s 



a 



pretty well agrees with that met with in the Lysianassida-. no essential 

 difference whatever being found to exist, 



1. Trischizostoma Raschi, (Boeck). 



(PI. 12). 

 Trischizostoma Raschi, Boeck, Crust. Amphip. bor, & arct. p. Ji. 



Body glabrous, moderately slender, with the back evenly vaulted 

 Cephalon rather short, narrowed interiorly, frontal projection liori/.ontal, 

 obtuse at the tip. Coxal plates scarcely as deep as the liodv. 1st pair very 

 small and partly covered by the 2nd; the latter greatly expanded inferior! v. 

 jutting out both anteriorly and posteriorly as a triangular loin-; the two 

 succeeding pairs almost equal-sized, obliquely oval, 4th pair truncated at tin- 

 tip and deeply emarginated posteriorly to receive the f>th one, the posterior 

 lobe of which is much deeper than the anterior; the '2 posterior pairs rather 

 small. Last pair of epimeral plates of metasome nearly right-angled. Kir.-t 

 segment of urosome deeply impressed at the base dorsal ly. Kyes successively 

 expanding superiorly, nearly confluent, though separated ly a narrow stripe 

 above in the middle. Superior antenme a little longer than tin- eephalon. 

 1st joint of the peduncle much longer than the other - eomliiin-d. llagellnm 

 it-articulate, with the 1st joint very large, accessory appendage alioiit the 

 length of the latter, triartieulate, the '2 outer joints very small. Inferior 

 antennae twice the length of the superior, penultimate joint of the peduncle 

 the largest, fiagellum composed of about '24 articulal ions. Anterior gnatho- 

 poda with the propodos greatly inflated, rounded triangular, forming anteriorly 



