402 l'liOCKElJl2iGS OF TUE NATIONAL MUHEUM. vol.xxi. 



SPHiERIODESMUS MEXICANUS (Saussure). 

 (I'latii XXXI, I'lKB. 1ft- lA.) 



(lloiimr'KlcHinuti rnvjicantiH Hauhsuhk, liiiiiioa l'-iil;()iii., IHftK, XIII, j». IWX; M<im. 



Mox. M.yriap., 1W50, p. IH, j)!. I, ligs. 1-1<'. 

 SphwriodeninuH mexicuniia I'ictkuh, MoiiiitHbor. K, Akad. WInh. lioiliii, 18(11, 



p.52!).— HAliHHtiKK and lIuMiticUT, KtiidoH, 1872, p. 21, pi. i, ligH. 1, 1/. 



Ti/pc. — Siipposod to 1)(^ in I'aris. 



IjocalUy. — Cordova, M«',xi(;(). 



Two HpccimouH of SpliariodaHmns have coiiio into my liaiidH loi' wJudy 

 tliroii^li (he kiiidiM'HS of Prolcssoi- Ki}U>,p(^Iiii, «lii(M;tor of Mic llainhiirg 

 MiiH(uiin. They seem Lo eoncHpoiid in every |)arti('iilar with the do- 

 HcriptioMH and i)hiteH eited above. They are from Vera Crnz, Mexieo, 

 vviiiie tln^ lype. <d' S. iiKwicdniis \va,H from Oordovai, only 7() miU^K away. 

 'I'hiiM, wliile it/ i.s well ni};h imiiosHibie in .some, lainilies of l)iph)[>oda to 

 li\ HpecjcH by divscaiptioiiH of external characters, an identification Heeins 

 ju.stilied in the present instance. 



Tlie details of the stinetiire of the copulatory le^H can ha better 

 underHtood from the phiteH, tl(^se not liavinj;' been i>reviouHly described 

 or li^nred. 



Ilnmbeit and Saussure j;ive the measurenKMits of tli<^ typical H|)eci- 

 mens as .'(li by HI mm., and state that th(\y liave four individuals meas 

 urin^;' 1(> by 5 mm. which they propose to eonsidcr provisionally as the 

 you 11}^ of the present species, although already provid(Hl with twenty 

 seji;tnents. These are indubitably a distinct species, i)robably of another 

 ^cniis. 



CYLIONUS, new genus. 



7'///;/;. — (U/iionuH gracilis (Humbert and Saussure), from Mexico. 



!<'rom the descriptions and plates of this sp(M>J(><s it appears that at 

 least a };('nei*ic, separation from tSjtiKcriodtsntiis is necessai'y. The 

 iiopulatory lejfs of tSphariodanniiiH are here made known for the lirst 

 time, and a. <'()mi)arison with the ])lates of (\ (gracilis shows a> com])leto 

 dil1er(MU',<i in lyjte i)\' structure. The resemblances is, in<le(Ml, with Dch- 

 monus, lather than with t^phariodcsmuN^ there bein^" a larj^e incurved 

 spine, presumably <'outaiuinj; the seminal duct. It appears, also, in 

 addition to the much smaller size (1 1 by 2.5 mm.), that the Ixxly is \\\\\v\\ 

 moi(^ strongly convex, laterally c(>mpr<^sse<l, and slender; the fourth 

 seii'meut is larjjer than the lifth; tins carina* of other.scfjrments are nar- 

 rower and sinuate posteriorly, and the last sejjment is loiifjfer and has 

 a. transverse depression or fuirow sonuiwhat above the posterior marp^in. 

 Moreover, from ones of the drawings it appears that Joint <» ol the 

 antennai is distinctly lon|j;(U' than Joint r». All the>.e dilfereneos point 

 in the iliicction of l>csnionns, but the enlarged fourth and lifth seg- 

 nuMits, and the want of any iu)ti«5(i of the riMuarUable dorsal pits of 

 J>CHnumus seem to foibid, for the present, reference to that vicinity, 

 and the {^enus is accoidinj^ly lel't near (^plKcriodcwiiis, where it may be 

 the more readily Ibund. 



