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Fett Sgn as ket tens MPRA TE tate tt ta hntaantn Ica meant, ieee e Breeeve saan nbn Nn, Matai ttenn ohn ns TEES bse ue : Cex PAATAL ? SEWITHSON Ay SeP 2 / WU riPrtasemeae S [)% famer,s—dourns Science ond Arts, XLIIy—Jduty;~ 1866s Sa @) ; ‘ ' | < LAAMOA , As Vl« wha VA, rat 3 | bs l; } 188 S. Ie Smith on new Crustacea from N. America, No. 1ll--Descriptions of a new genus and two new from North Americas by Sidney 1. Smith. Evibacus, Bene nove Carapax very broad; lateral border expanded, inci-= sion at the cervical suture closed, and the margin behind it not incised. Rostrum broader then long, very slightlv bilobed. Eyes situe- 8. I. Smith on new Crustacea from N. America. 119 ated midway between the rostrum and the outer angle; the orbits entire, slightly removed from the anterior margin and connected with it only by a suture. Antenne with the inner margins approximate. : This genus is most nearly allied to I[bacus and Parribacus but is very distinct from both of them in the entire lateral mar- gin of the carapax, the closing of the orbits in front, and the form of the rostrum. Hvibacus princeps, sp. nov. Whole upper surface verrucose and nearly naked ; five low, tuberculose elevations on the median line of the carapax, of which one is at the base of the rostrum, two on the gastric re- gion, one on the anterior part of the cardiac, and one on the posterior margin ; similar elevations on the middle of the sec- ond and third serments of the abdomen, and a very slight one on the fourth. Carapax strongly convex transversely ; the an- terior margin nearly straight, except at the lateral angle where it is slightly curved forward ; lateral margin strongly curved, with a broad notch at the cervical suture behind which the margin is very slightly, obtusely and irregularly toothed. An- tenn together as broad as the anterior part of the carapax ; the outer margins coarsely and irregularly serrate and their out- line forming the segment of a circle. Hverywhere beneath naked and nearly smooth. External maxillipeds with the outer margin of the merus divided into a number of slender proces- ses. Legs so short that when bent forward in their natural position they are concealed beneath the expansions of the car- apax ; those of the first and second pairs with the superior angle of the merus raised into an obtuse crest; dactyli of all the legs short and stout, in the female those of the posterior pair closing against a process from the propodus. Abdomen with the lateral projections of the second, third and fourth segments long and rather acutely pointed, those of the fourth shorter and triangular at tip ; lamella of the terminal’ segment half as long as broad. Whole length of body, 14 in. ; leneth of carapax, including rostrum, 5:8 ; breadth of carapax, 7:9. A single female specimen of this remarkable species, the first of the Scyllaridz discovered upon the west coast of America, was sent from La Paz, Lower California, by Capt. Jas. Pedersen. Arctus Americanus, sp. Nov. Carapax as broad as long, median crest high, covered with low squamiform tubercles, tridentate, the anterior tooth small and situated half way between the front and the second tooth ; lateral crests very high, anterior portion with two teeth above the eye and separated by a deep notch from the posterior por- 120 S&. I. Sith on new Crustacea from N. America. tion which is covered to the lateral margin with low squamiform tubercles ; depression between the median and lateral crests broad and deep, smooth or slightly punctate, with a median line of four depressed tubercles ; lateral margin broken by a deep fissure at the cervical suture, and by a slight one a little more posteriorly. Antipenultimate segment of the antennee as broad as long ; anterior angle not prominent ; outer margin arcuate, bidentate ; anterior margin armed with several denti- cles ; median carina prominent but smooth and even ; terminal segment short, the extremity almost truncate and rather deeply five-lobed, the lobes rounded; the inner margin bidentate. Exposed portions of the abdominal segments sculptured as if covered with rows of scales ; fourth segment with a prominent median elevation above. Feet nearly naked ; the merus seg- ments slightly carinated above. Length, 1:45 in.; length of carapax, along the median line, -45, lateral margin, -50; breadth, anteriorly, ‘49. Male and female do not differ. Several specimens from Kemont Key, west coast ot Florida, collected by Col. E. Jewett and William T. Coons. It is spe- cially interesting as the representative of a genus hitherto known only from the old world. Aithra scutata, sp. nov. Carapax transversely and regularly elliptical ; margins thin, slightly dentate, the denticles separated by broad and very shallow sinuses ; posterior margin nearly straight in the mid- dle ; anterior margin straight and parallel to the posterior margin for a short space outside the eyes; front projecting horizontally, its margin forming a semicircle; gastric region elevated, with a broad median depression extending to the front ; anterior lobe of branchial region large and prominent ; the broad space between the branchial region and the antero- lateral margin concave ; summits of the elevations and a space along the posterior border tuberculose, rest of the upper surface smooth ; inferior lateral regions slightly convex and smooth. Chelipeds fitting closely to the carapax ; the angles projecting into dentate crests ; outer and inferior surface of the hand coarsely granulous. Ambulatory legs short ; the angles pro- jecting into thin, dentate crests, Sternum and abdomen deeply vermiculated. Length of carapax, 1:39 in. ; breadth, 2:23. A single male of this species, the first of the genus dis- covered in America, was sent with the Hvibacus from La Paz by Capt. Pedersen. It is at once distinguished from ZH, scru- posa Kidw., by the much broader and more regularly elliptical carapax. The genus 4thra should evidently be placed near Crypto- Physics and Chemistry. 121 podia as has been done by Stimpson. The gastric region is narrow and projects far forward as in the Maioids. The ex- pansions on the sides of the carapax, which give it a Cancroid form, are thin, and contain none of the internal organs, and their removal would give the carapax very much the form of Cryptopodia.