[PROM THE AMERICAN JOURNAL OF SCIENCE AND ARTS, VOL. XV", MAY. 1878.] 



Descriptions of new Genera and Species of Isopoda. from New 

 England and Adjacent Regions ; by OSCAR HARGER. Brief 

 Contributions to Zoology from the Museum of Yale College. 



THE genera and species described in the present paper are, 

 except the first, marine and were, mostly, collected by the 

 United States Fish Commission, along the New England coast. 

 More complete descriptions with figures of all th'e new, and 

 most of the old species, are nearly ready for publication in the 

 Report of the Commissioner. As it seems desirable, however, 

 to give a wider publication to the genera and species believed 

 to be new, the following diagnoses are here inserted. 



Actoniscus, gen. nov.* 



Eyes small. Antennae geniculate at the third and fifth seg- 

 ments; flagellum four-jointed. Terminal segment of maxilli- 

 peds lamelliform. Legs all alike. Pleon of six distinct seg- 

 ments. Basal segments of uropoda dilated and simulating the 

 coxae of the preceding segments ; rami both styliform. 



This genus belongs to the Oniscidce, and is near Acfcecia Dana, 

 MSS. (U. S. Expl. Exped., Crust., part n, p. 736, pi. 48, fig. 6), 

 regarded as the young of ticyphax, but considered by Kinahan 

 as the representative of a distinct family of the Oniscoidea. 



A. ellipticus, n. sp. Body oval. Head with a prominent 

 angular median lobe, and broadly rounded, divergent lateral 

 lobes. Eyes oval, longitudinal, prominent, black. Antennulae 

 rudimentary. Antennas nine-jointed ; first segment short ; sec- 

 ond strongly clavate ; third smaller, clavate ; fourth flattened- 

 cylindrical ; fifth longest, slender, bent at the base; flagellum 

 shorter than the fifth segment, composed of four subequal seg- 

 ments, tipped with setae. Terminal segment of maxillipeds 

 elongate triangular, ciliated and slightly lobed near the tip. 

 First thoracic segment excavated in front for the head, shorter 

 above than the following segments except the last, which is short- 

 est. Legs small, scarcely spiny. Pleon continuing the regular 

 oval outline of the thorax, apparently with four pairs of lamel- 

 lar coxaa, the last pair are, however, the enlarged basal seg- 

 ments of the uropoda and are notched on their inner margins 

 for the short outer rami, while the more slender inner rami are 

 borne lower down on the under surface. The rami scarcely pro- 

 ject beyond the general outline. 



This species has been collected by Professor A. E. Verrill, at 

 Savin Rock, near New Haven, and also at Stony Creek, in com- 

 pany with Philoscia vittata Say. 



* Prom aKTij, the beach, and Oniscus. 



