NO. 1154. AMERICAN MEROCHETA— COOK. 453 



iSftcond Hef^mcnt larfjf'Ht, tlio carinic liroad and (■xi)anded downward to protect the 

 sides oftholiead; roi)iij^natorial pores preHent; siipplciiicntary iiiiMj^iii pectinate; 

 last segment niucb l)roa(l(!r tlian long, the poaterior margin notclicd and tnberculate: 

 Family Cyutc)i>|.;,smii),k. 



Second segment distinctly smaller tlian the third; repngnatorial pores wiuiting; 

 Biipplementary margin entire or wanting; last segment nearly an long as broad, the 

 posterior margin an entire, tiiin (idge 



Carina; increasing in size to segment 5; segments 1 and .5 with carime much larger 

 than B(!gment '^^, antenniie rather slender, Joints .^> and (J 8iil)e(|iial : Fiimily Simi.i;- 

 inoDESMio.K. 



Carinie increasing in size only to segment 3, which is much the largest; antenna* 

 rather robust, joint 5 distinctly shctrter than (5 



Surface of segments smooth, even, and polished, withr)ut pores or depressions of 

 any sort: Family Cycm)Oic.smii),i;. 



Surfae%> of segments granular-hispid; j)osterior subsegnientH convex or witli a 

 transverse row of conic tuliercles; at the base of the caiinii' in front a large, deej) 

 cavity: Family Dk.smonid/K. 



Family ONlSCODESMIDyl^: (Saussure). 



OniHcodesmides Sau8kukk, Mem. Mex. Myriap., I8Go, p. 14. 

 Oiiincodenmida: Cook, IJrandtia, 18!Mi, p. 2S. 



Jjody very small, lews than three times as long as broad; dorsum 

 strongly convex, the carinas very broad, sloping obliquely downward; 

 surface of segments smooth, the jiosterior margin ornamented by a 

 tiansverse row of rectangnUir areas. 



Antenna; robust, subclavate, joint 5 over twice as long as joint 0; 

 joints 2 to 5 sube(|ual in lengtli. 



Second segment with carina; much tiic laigest of all, broadly 

 expanded and extending obliquely downward beyond the level of the 

 others. 



Lateral carina; triangular, entire. 



Repngnatorial i)ores distinct, located near the middle of the base of 

 the carina*. 



Suppl(!nuintary margin wanting. 



Last segin(;iit small, the ai)ex r-ounded and de])ressed, more or less 

 conceaIe<l by the mu<*,h larg(!r penultimate segment. 



(Jopulatory legs strongly divaricate, consisting of two rami, subequal 

 in size and length. 



The aflinities of OniscodcHmuH ajid its allies are (evidently with the 

 Pterodesmidic and other forms generally arranged near Cryptodesrmis. 

 The transverse posterior row of rectangular areas are the most con- 

 spicuous evidence of this relationship, which is also indicated by the 

 location of the pores, the short and robust antennae, and the form of 

 the Terminal segments. This last feature sejjarates the Oniscodesmida; 

 readily from all other Ameri(;an Meiocheta adapted for Ijcing rolled 

 into a sphere or close spiral. 



In none of the known ()nis(;ode.sn)ida' is the last segm<;iit larger than 



