53 



broad, armed on the inner edge with small claw-like spines, basal lobe 

 obtusely truncated at the tip, palp rather large, dactyl us slender spinit'onn. 

 Both pairs of guathopoda very slender and about of same length, the anterior 

 ones with the propodos narrow and elongated, provided at the tip with a double 

 row of delicate setse, dactylus replaced by a dense brush of hair-like setae, 

 though a claw-like rudiment may be found on closer examination ; propodos 

 of the posterior pair produced at the tip beneath the dactylus, thus forming 

 a minute chela. Pereiopoda rather strong, the 3 posterior pairs successively 

 increasing in length; basal joint very broad, laminar; meral joint likewise 

 considerably dilated, especially in the third pair. Last pair of uropoda 

 considerably projecting beyond the preceding pair, rami subequal, denticulated 

 and setoiis. Telson elongated and narrow, deeply cleft. 



Remarks. - The present genus was established by Costa as early 

 as 1851 for a Mediterranean species C. Hopei, to which was subsequently 

 added by the same author another species C. punctatum. The genus Scope! o- 

 cheirus established by Sp. Bate in 1855 for a British species, is undoubtedly 

 identical with the genus of Costa and thus must cede to the elder name 

 Callisoma. It is a very distinct genus, differing from the other Lysianassidae 

 both in the structure of the oral parts and especially in that of the gnatho- 

 poda, the anterior pair of which are very peculiarly constructed. Two close 1 v 

 allied, though evidently distinct, species belong to the Fauna of Norway. 



13. Callisoma crenata, Sp. Bate. 



(PI. 19, fig 1). 

 Scopelocheirus crenatus, Sp. Bate, Brit. Assoc. Report 1855. 



Body rather robust, with broadly rounded back. Cephalon comparatively 

 small, lateral corners but slightly projecting and narrowly rounded. Firsl 

 pair of coxal plates rather broad, completely obtecting at the sides the buccal 

 mass, their anterior and inferior edges forming a quite continuous curve; 

 pair deeply emarginated posteriorly and below the emargiiiatioii angularly 

 produced; 5th pair much broader than they are deep. Last pair of epimerul 

 plates of metasome rounded at the lateral corners, posterior edge irregularly 

 crenulated. First segment of urosome having dorsally a deep transversal 

 incision, below which there is a rounded carina, Eyes broadly oval, pigment 

 reddish brown with an orange-coloured coating. Superior antennae about 

 twice the length of the cephalon, peduncle short and thick, especially in the 

 male; nagellum 10 12-articulate, 1st joint in female about the length of the 

 3 succeeding joints combined, in male nearly occupying the half Length <>t 

 the nagellum; accessory appendage 3-articulate. Inferior antennae in female 



8 Crustacea. 



