AMPELISCA. 125 



A MPHIP ODA. A MPELISCIDES. 



NATATOKIA. 



Genus AMPELISCA. KROYER. 



.1 mpelisca. KROYER, Nat. Tidskr. 1 ser. iv. p. 154, 1842. SPEXCE 



BATE, Ann. Nat. Hist. ser. 2, vol. xx. p. 255. Cat. 

 Amph. Brit. Mus. p. 90. LILJEBORG, Ofvers. af 

 Kongl. Vetensk. Akad. 1851, p. 22 ; 1855, p. 137. 



Araneops. COSTA, Rend, del Accad. del Sc. di Nap. 1853, p. 169. 



Pseudophthalmus. STIMPSON, Marine Invert. Grand Manan. Proc. Nat. H. 



Soc. Boston. 



Tctromatus. SPEXCE BATE, Brit. Assoc. Eep. 1855, p. 58. Ann. Nat. 



Hist. ser. 2, xix. p. 139. WHITE, Hist. Brit. Crust, 

 p. 171. 



Generic characters. Cephalon produced, and tapering an- 

 teriorly Eyes four, simple, two situated on each side, near 

 the extremity of the cephalon. Superior antennae at the ex- 

 tremity of the cephalon, without secondary appendage. Inferior 

 antennae placed very far posteriorly to the superior. Mandibles 

 having an appendage. Gnathopoda imperfectly subchelate. Pos- 

 terior pair of pleopoda biramous. Telson squamiform, cleft. 



THE animals of this very curious genus have the body 

 long, smooth, and more compressed anteriorly than pos- 

 teriorly, so much so that the anterior portion of the 

 dorsal surface presents a wedge-shaped appearance, but 

 scarcely carinated. The head gradually tapers in front 

 to an obtuse point, at the extremity of which the su- 

 perior antennae are situated. The eyes are placed near 

 the extremity of the head, and consist of two small 

 simple organs upon each side, four in all, whence the 

 generic name " Tetromatm" we had proposed, at the 

 suggestion of our excellent friend, Mr. Adam White. 

 The superior antennae are without a secondary append- 



