of the North Atlantic and of North- Western Europe. 637 



1894. Cylindroleberis teres, . . Muller, G. W., " Die Ostracoden des Grolfes von 



Neapel.," p. 220, pi. iv., figs. 13, 30; pi. v., 

 figs. 15, 24, 25 ; pi. viii., fig. 5. 



Shell of female (PI. Lii., figs. 20, 21) regularly oval, greatest height rather 

 behind the middle, equal to fully two-thirds of the length; ventral and dorsal 

 margins both well arched throughout, the latter rather more boldly than the 

 former ; posterior extremity very broadly and evenly rounded ; anterior extremity 

 narrower than the posterior ; antennal sinus very narrow and shallow, situated 

 below the middle, and nearly erect ; rostral process moderately wide at the 

 extremity, and bending over the antennal notch. Seen from above the form is 

 more tumid than in other species of the genus ; greatest breadth near the hinder 

 extremity, which extremity is much broader than the anterior, and well rounded, 

 sides arcuately sloping forwards. Surface of valves white, polished, finely punc- 

 tated, glabrous. Length 1*6 mm. Third joint of tlie antennules (PI. l., fig. 8) 

 much shorter than the fourth, divided diagonally so as to form two triangular 

 joints, the outermost of which bears eight closely-packed marginal setae ; sensory 

 organ as in A. marice ; unguis long and slender, its edge crenated ; terminal setse 

 very long, the setae themselves terminating in lashes of similar character to 

 those which spring from their sides. Appendicular branch of antennae papilliform 

 (fig. 7), scarcely more than twice as long as its greatest width, indistinctly 

 articulated, the end rounded, and bearing a long terminal seta, which is the only 

 seta the limb bears. Laminar appendage of first joint of mandibular palp well 

 developed, equal in length to two-thirds of the second segment, and its apical setae 

 stretching forward over the third segment. The first maxillae are distinctly 

 jointed at the union of the ciliated portion with the naked extremity. Caudal 

 laminae more than twice as broad as the length in front, the arch of the 

 extremity, which is formed by the posterior and distal margins, surrounded 

 by ten ungues, which gradually increase in length, the larger ungues marginally 

 ciliated. 



In the male the antennules have one recurved plumose seta on the second joint, 

 six on the short triangular third joint, which is longer than the fourth joint on the 

 front margin, but excessively short on the hinder margin ; the large brush-like 

 sensory oi'gan, and the two long terminal setae as usual. The antennae, apparently, 

 have only one seta on the second joint of the appendicular branch, the falcate last 

 joint of which is equal in length to half the preceding. The terminal unguis of 

 the mandibular palp is long and slender, equal in length to the two preceding 

 joints; the penultimate joint has seven spines and setae on the front margin, and a 

 transverse group of small setae on the face (as in A. marice). The vermiform limb 

 has both of the apical lips serrately divided, and bears twelve spines. The ungues 



IfiANS. BUY. UUii. SOC, N.S. VOL. V., PARI XII, 4 X 



