NO. 2165. NEW PARASITIC I80P0D CRUSTACEANS— HAY. 571 



SYNSYNELLA, new genus. 



Branchial parasites. Head and first thoracic segment completely- 

 fused in both sexes. Eyes present. Uropods wanting. 



Female. — Body somewhat asymmetrical. First and second tho- 

 racic segments and first four abdominal segments fused in the middle 

 region, but free at the sides; last two abdominal segments completely 

 fused; other segments distinct. Pleopods usually rudimentary but 

 with indications of being biramous. 



Males. — Body symmetrical. Abdominal segments five, all dis- 

 tinct. Pleopods wanting. 



This genus, which probably stands closest to Bopyriscus Richard- 

 son, differs from all other genera of the family Bopyridae in the com- 

 plete fusion in both sexes of the first thoracic segment with the head. 

 This condition, according to Dr. H. Richardson,^ is paralleled in only a 

 fewisopods, namely in the family Tanaidae, the family Dajidae (males 

 only), the family Serohdae, and in the species Crahyzos longicaudatus 

 Spence Bate and Ardurides comutus Studer and the genus StenaseUus 

 DoUfus. The union of the second thoracic segment with the head 

 mass, as shown in the female of the present species, is a stiU rarer 

 condition, being known only in the genus SpJiyrapus Norman and 

 Stebbing. 



Ty2)e of the genus. ^Synsynella deformans, new species. 



SYNSYNELLA DEFORMANS, new species. 



Plate 99, figs. 13 to 18. 



Holotype and paratypes. — Female, Cat. No. 48371, U.S.N.M., Cat. No. 

 48372, U.S.N.M., from Onslow Bay, North Carolina, about 20 miles off 

 Beaufort Inlet, parasitic on SynalpTieus longicarpus (Herrick) ; depth, 

 10 fathoms, station 8293, United States Fisheries Steamer Fisli Hawk; 

 August, 1915. 



Female. — Body nearly symmetrical, shghtly longer on one side than 

 on the other, about two-thii'ds as wide as long. Color entirely wliite 

 or wliite with a brown area on the dorsal surface. Eyes red. Head 

 broad, completely consolidated with the first thoracic segment, but a 

 deep notch on each side continued into a shallow groove indicates its 

 margins. Second segment fused with the first in the middle, but free 

 at the sides. The other thoracic segments distinct. Epimeral plates 

 present on the second, tliird, and fourth segments on both sides of the 

 body, but smaller on the short side. Ovarian bosses entirely lack- 

 ing. Abdomen composed of six segments fused together along the 

 middle fine ; the first four have their outer hah or two-thirds free, the 

 last two are completely fused; the outer ends of all turn backward 

 and from front to back are increasingly acute. First lamella of the 

 marsupium bilobed, those of the two sides approximately ahke in 



I Proc. U. S. Nat. Mus., vol. 27, 1903, p. 9. 



