Portal de Periódicos da CAPES

The Phreatoicoidea. Part II

1943; Linguagem: Inglês

10.26749/sebt4788

0080-4703

GE Nicholls,

Historical, Religious, and Philosophical Studies

sentatives being forms retaining• what must be assumed to be the docked stump only of a lJl'imarily elongate telson, reduced mouth parts, and uropods but slightly armed.This stump of the telson bears a te1•minal fringe of spines, in the great majority four in number.Such an armature characterizes the telsonic apex, not only of the species of Pantphreato•icus, but also of a very wide range of members of this sub-order, •and it may well have been the number originally preserved on this tel sonic stump.A few, however (constituting the genus M etaphreato•icus), have six spines, an arrangement which might represent either an intermediate condition in the reduction of the telson, or be due to a secondary acquisition of a third pair of these spines developing upon the lateral border of the stump.In the present account it is regarded as secondary, (1) and the more general armature of four spines is considered as the earlier condition in this family.KEY TO GENERA A. Eyes large, prominent; tebon with terminal projection well developed, its pleura slig•htly produced; g•nathopod with spines on palm denticulate ; spine beneath insertion of rami of uropods stout, toothed.B. Telsonic projection cylindrical, backwardly directed.C. Telsonic projection relatively long, segments of peraeon deepe1• than long; bases of hinder peraeopods not expanded 11fesacnnthotelson Cl.Telsonic projection shortened; peraeon segments as long as deep; base3 of hinder peraeopods slig•htly expanded Colacanthotclson E 1 .Telsonic projection slig•htly flattened, sharply upturned; segments of peraeon deeper than long A 1. Eyes small or wanting•; teL'5onic projection reduced to sn1all upturned stump ; pleura of telson well developed; ~;rnathopod with spines on palm denticulate; spine beneath insertion of rami of uropod stout, toothed.B. Apex of telsonic projection arn1ed with two pairs of spines.C. Endopodite of first pleopod setose C1• Endopodite of first pleopod without setae B 1 • Apex of telsonic projection with three pairs of spines A'2.Eyes wanting; telson scarcely produced or upturned.its hinder dorsal border having an outline ranging from sub-triangular to a •flattened convex; gnathopod with palm armed with stout sub-conical spines.B. Body vermiform, telson with flattened posterior surface; spine beneath insertion of rmni of uropods stout, shnple.C. Gnathopod practically chelate; bases of hinder peraeopods not expanded C1 • Gnathopod sub-chelate; bases of hinder peraeopods n1oderately expanded B 1 .Body sub-cylindrical, fusiform; bases of hinder peraeopods scarcely expanded.C. First pleopod with endopodite bearing plu1nose setae; penial stylet cylindrical with several terminal spines; spine beneath inHer-Onchotel::wn