28 MR. E. J. MIERS ON CRUSTACEA FROM [Jan. 14, 



and emarginate rostrum. It is extremely difficult to find reliable 

 characters by which to define the genera, as the species pass into one 

 another by almost insensible gradations. At one end of the series are 

 those which belong undoubtedly to the genus Libinia, in which the 

 carapace is triangulate rather than orbiculate, with a distinct supra- 

 ocular tooth, the rostrum prominent, with the spines coalescent and 

 divergent only toward the apex, which thus appears notched, the 

 orbits circular and well defined, with usually a single closed fissure 

 above, the basal joint of the antennae moderately dilated, and the legs 

 usually of moderate length, the first pair rather slender in the male. 

 At the opposite extremity of the series are the species of Doclea in 

 which the carapace is orbiculate in outline, the rostrum very short, 

 the supraocular spine absent, the basal joint of the antennae narrower, 

 the orbits scarcely defined at all below, the legs usually very long, 

 those of the first pair in the male short, with the palm dilated. The 

 genus Libidoclea ot Milne-Edwards and Lucas is somewhat inter- 

 mediate between the two former, having the triangulate carapace, 

 prominent rostrum, dilated basal antennal joint of Libinia, with the 

 incomplete orbits and long legs of Doclea ; the typical species, L. 

 granaria (Edw. & Luc. in D'Orbigny's Voy. Amer. Merid. vi. Crust, 

 p. 8, pi. iii. fig. 1 & pi. iv. fig. 1, 1845), from Valparaiso, possesses an 

 additional character in the existence of a notch on the anterior mar- 

 gin of the third joint of the outer maxillipeds ; and the tooth in the 

 middle of the outer margin of the basal joint of the antennae is very 

 strong; the former of these fails, however, in the Libidoclea coccinea 

 of Dana (U.S. Expl. Exp. xiii. Crust, p. 88, pi. i. fig. 3), from Pata- 

 gonia, which also has a shorter rostrum. Li certain species of Libi7iia 

 {L. emarginata) there is a small blunt tooth on the outer margin 

 of the basal antennal joint. There appears, then, to be no alter- 

 native between restricting the genus Libidoclea, by adopting the 

 single character of the emarginate third joint of the outer maxillipeds, 

 or extending its definition until it shall include all the species inter- 

 mediate between the two older genera. The former is perhaps the 

 preferable course, as, if the latter were adopted, it would be impossible 

 to assign any definite characters to the genus. 



Doclea orientalis, sp. n. (Plate IL fig. I.) 



The carapace is convex and subpyriform, with six tubercles in the 

 middle line, of which the first three are on the gastric, two (one more 

 elevated) on the cardiac, and one on the intestinal region ; none of 

 these are large and spiniform. There are two prominent tubercles on 

 the lateral anterior margins, one of them placed at some distance be- 

 hind the orbits, and one on the sides of the branchial region. There 

 are four small tubercles on the front of the gastric region, forming, with 

 the first of the median series, a figure * • * , seven or eight on the 



branchial region, on each side, and three on the pterygostomian region. 

 The rostrum is short, but little longer than broad, and notched to 

 its middle. The orbits have a supraocular tooth, a wide hiatus above, 

 and two fissures below. The basal joint of the antennae is rather 



