76 Mr. C. Spence Bate on a new Oenus of Macrura. 



multiarticulate basecphysis that reaches beyond the distal 

 extremity of the dactylos, which is sharp-pointed, slightly 

 curved, and imbedded among a number of fringed stiff hairs ; 

 a small branchial plume stands on the outer frontal surface of 

 the coxa. 



The second pair («') resemble the first, but have the joints 

 longer and more slender and furnished with hairs that are 

 more slender and fringed with delicate cilia instead of short 

 spines. The basecphysis, although absolutely longer, is rela- 

 tively shorter than the limb to which it is attached and 

 articulates with the basis at the extremity of a strong process, 

 which is an unusual feature. 



The four anterior pairs of pereiopoda (n) are similar in 

 form and vary little in size ; they are all chelate, but ineffi- 

 ciently so ; the pollex and dactylos being straight and pointed 

 appear to be organs ill adapted for the purpose of holding as 

 by a finger and thumb ; each joint is furnished with one 

 or more long, straight, and ciliated hairs. The basis is long 

 and robust, being with the coxa nearly equal in length to 

 the other five joints ; at the anterior and distal extremity 

 is a multiarticulate basecphysis which reaches considerably 

 beyond the extremity of the dactylos and is fringed on the 

 posterior margin only with numerous ciliated hairs. The coxa 

 supports a long podobranchia and a small mastigobranchial 

 plate of a rudimentary character. 



The fifth pair (o) are shorter, being little more than half the 

 length of the preceding ; they terminate in an obtuse-pointed 

 dactylos, and have an ecphysis attached to the basisal joint. 



The pleopoda are biramose, with subequal branches, and 

 weak in their development. The posterior pair form the 

 lateral plates of the rhipidura or tail-fan ; but the plates are 

 about one fourth shorter than the telson. The outer plate is 

 broader than the inner, which is narrow, pointed, and a little 

 shorter than the outer, which appears to be without a diasresis. 



EXPLANATION OF PLATE IX. 



Fig. 1. Ophthahneryon transitionalis, seen dorsally. 

 Fig. 2. The same, viewed ventrally. 

 Fig. 3. The same, seen laterally. 



a. Ophthalmopod. h. Fii'st gnathopod. 



b. First antenna. i. Second „ 



c. Second „ n. First pereiopod. 



d. Mandible. o. Fifth „ 



e. First siagonopod. v. Sixth pleopod. 



f. Second „ z. Telson. 



g. Third „ 



