598 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



Specimens of .1. f/ayi in the U. S. National Mnseum have been iden- 

 tified by comparison with a tyi)e in the mnscuni of the IMiihidelpliia 

 Academy of Sciences. Professor Stnrany, of tlie musenm in Vienna, 

 has kindly determined as the same species the type specimen of A. 

 l/at/i I Idler, 1805 { = ]*l(((/i(srtes clatus Heller, 18()2). The existence of a 

 third species was discovered by Dr. Walter Faxon, wiio tnrned his 

 notes and specimens over to me. The general api)earance of the three 

 species is much the same. The dilferences are constant and can best 

 be expressed in the following table: 



('liiiriicleriiiticH of spvcica of Afunlhocj/clua. 



1. A.gayi. 



Narrow; widlh l.Of) to 1.08 



liiius Icii^itli. 

 I-iit(iiiil tpctli intoriiuHliiito — 



Kroiil ciiliro 



l)ii(l\li of aiiiliulatory Iojjh 



.slioi't, iiiiK'li riirvud. 

 ICnil ol' biiHiil iinti'iinal Joint 



HWolliMi in a wide, Hiiiootli, 



roiiml |)i<>tiil)criiiirc ctirv in;.; 



o\(M-on lo tlio liont. 



Alidoincn of male narrow; 

 HidcN of I'ourtli, lit'Mi, and 

 Mixtli H(^;;ni(intH Hnliparallid. 



Jiodi t^arajiaco and legs very 

 Iniiry. 



Carapacn alniosd Hniootli 



iHcliiiini Joints of nnixillipcilN 

 with inner margins Hiil)|>ar- 

 »\M, but Idavinj; a wido liia- 

 Ills. 



l^loruH Joints of niaxilli)UMlH 

 witli tlii'ir onlor margins 

 Hnl)purall(<l and t'ontinnons 

 with tlio outoi' niarjiins oC 

 tlio iscliiiini Joints. 



Orbit viewed tVom aliovo less 

 llian t wieo as wnltf as docp. 



2. A . ttlhatrossiu. 



Width inlerniediale, l.OS In 

 limes leriKlli. 



Teetli pi'oniinent, acute 



Front laintly bilolxid 



Dac'tyli lonf;, littl<< enrved. 



Anteunal Joint not Hwolloii at 

 tho very eml, lint t'urnislied 

 witlial)lnnl, projeetiiif; tuotli, 

 betwoMi wliieli and llie front 

 a narrow furrow rnns. 



AlidoMien wid<t; sides of {]w 

 sixth Ho;.'nH'nt eonvex, of tiftli 

 <'oneavt>, id' tliinl and fonrtli 

 convorgiun distolly. 



Lush hairy. 



Carapace tulll^l•cnlate 



Iscliiiiin Joints with innur mar- 

 gins in contact. 



Morns Joints divorfjonl, i. e., 

 their outer margins malvc 

 i|uite an angle willi tluMintei- 

 nuirgin of tlm iscliinm Joint. 



Orbit viewed from above less 

 than twieo as wide as deep. 



3. A. hastleri. 



Wide; widtli l.lfl I ime.s 



lengtli. 

 Tcetii appressed. 

 Friuit entire. 

 Dae tyliMhort,nincli curved. 



Antennal Joint as in alba- 



trotnig. 



Alidomon intermod iate ; 

 sides of tlie sixtli seg- 

 ment convex, of tilth 

 Htraiglil, of tliird and 

 fourth <iinverging dis- 

 tallv(Plate\LlIl,tig.l). 



Less hairy. 



(!ara)ia(^o tnberculatc. 

 l.schium Joints witli inniM- 



nnirgins diverging anlt^- 



riorly ; gape Ioh.s tlian in 



O'llii- 

 M(<ru8 Joints similar to 



those of .'/irj/i. 



Orbit viewed from above 

 more than twice as wide 

 as deep. 



The synonymy and distribution of the species are given below, so 

 far as known. A. <(lh((tn>ssi,s is the only species represented in the 

 collection which forms the siibjecit of this paper. 



ACANTHOCYCLUS GAYI Milne-Edwards and Lucas. 



Aranthocychin{iayi Mii.NK-EinvAKD.s jind Lucas, D'Orbijjny's Voy. rAnuT. Morid., 



18'i:{, VI, i't. 1, p. 30; 18.17, IX, pi. xv, (ig. 1. Vali)ariiiH(). 

 Aoanthocy chili (jaiii NiOoi.Ki", in (Jay's Hist. Chil<s Zool., IHDt, III, p. 17(). (Trtins- 



lation and abbrtwiiitlou, for tho nio.st part, of Mihio-Kdwards's de.scriptioii.) 



\'iilparaiH(). 

 Avaiilhoci/vliis riUosiin Stkaiii., Moiiats. AUad. Wiss. Itcrliii, .Inly2r>, 18(51, 1802, 



p. 7115, ])late. 

 ricuiHsetescIatiiH IIi<:i,i.kr, Vorh. (Jos. Wion, 1H()2, XII, Pt. 1, p. .5L'2 [1 ]. CMiilc. 

 Acanthociidnx ijatji 1Iki-lki!, Kciso Fregatto Novara, 18G5, II, l*t. 3, Crtist., j). 70. 



Chile. 



