NO, 2253. DESCRIPTIONS OF TEN NEW ISOPODS— BOONE. 599 



segment is domelike with the posterior margin evenly roimded. The 

 two branches of the iiropoda are about of equal length ; the fixed in- 

 ner branch is oar-blade shaped ; the movable outer branch is more ta- 

 pering posteriorly and has the outer margin distinctly tridentate on 

 the right uropod, and bidentate on the left. The margins of the ter- 

 minal segment of the abdomen of both branches of the uropoda are 

 fringed with very minute, closely set hairs. 



The entire body surface is marked with fine brown pigment spots ; 

 dense granulations arranged in longitudinal ridges occur on either 

 side of the thoracic segments, and a double row of coarse granulations 

 borders the posterior margin of each thoracic segment, which is dis- 

 tinctly carinated. 



The holotype (Cat. No. 5040T, U.S.N.M.), comes from Mariveles, 

 Luzon, Philippine Islands, and was collected by Mr. Albert M. 

 lieese. 



The species is unquestionably a form intermediate between the two 

 genera S'phaeroTJUi and Exos])haeroma., more pronouncedly so than 

 Exospha€ro7mi crenulatuTn Richardson ^ or SphaeroTna. glohicauda - 

 Dana, and after a critical examination of the types of many species 

 of both genera, I feel it is probable that the finding of additional 

 specimens will make it imperative to unite these genera. 



EXOSPHAEKOMA BARRERAE, new species. 



Plate 90, figs. 2, 4. 



Body elongate-ovate, convex, very contractile; length, 13.5 mm., 

 v\^idth 7 mm. 



Head subcrcscentic, anterolateral margins produced, entirely con- 

 cealing the antennae. Eyes large, round, compound, situated in the 

 extreme postlateral region of head ; the posterior margin of head be- 

 tween the eyes is decidedly carinated. The first antennae are about 

 four-fifths as long as the second pair, and have the first and second 

 articles of the peduncle decidedly swollen, the second being much 

 shorter than the first; the third is long and slender and the flagellum 

 consists of 20 articles. The second antennae extend backward and lie 

 under the epimeral plates of the first to third thoracic segments, 

 reaching to the anterior margin of the second thoracic segment; the 

 peduncle consists of five subequal articles and the flagellum of 19 

 articles. The maxilliped has a palp of three articles. The mandible 

 has a palp of three articles. 



Thorax : The first segment is 2 mm. long, with the lateral margins 

 decidedly expanded and produced anteriorly, surrounding the ante- 

 rolateral margin of the head; also expanded and acutely produced 



^ Exospliaeroma crenulatum Richardson, Trans. Conn. Acad. Sciences, vol. 11, 1902, 

 pp. 292-293, pi. 39, fig. 40. 



^ Sphaeroma glohicauda Dana. Stebbing., T. R. R., The Fauna and Geography of the 

 Maldive and Laccadive Archipelagos, vol. 2, pt. 3, 1905, p. 710. 



