OF WASHINGTON. 299 



A NEW MEXICAN DIPLOPOD, DECAPORODESMUS MOTZO- 



RANGI NIS, TYPE OF A NEW FAMILY, 



DECAPORODESMID^. 



By F. C. KENYON. 



The single specimen upon which this description is based was 

 found in a lot of myriapod material collected by Mr. Lawrence 

 Brunei* in Mexico. The specimen is about 8 mm. in length, 

 relatively slender, of a warm, brown color above, and lighter 

 below, and with peculiar structural characters that readily dis 

 tinguish it from all other known American diplopods. The seg 

 ments are of the usual number found in the polydesmid group, 

 but relatively short and loose. Or, in other words, the inter- 

 segmental membrane is prominent. The lateral carinae are 

 prominent, not decurved, and with the outer margin provided 

 with a median notch that gives it a bituberculate appearance. In 

 the first segment, which is large, they unite in front so as to form 

 a broad plate overhanging and completelv concealing the head. 

 The margin of this plate is provided with ten tubercles. In the 

 second segment the carinas project forward, and the outer margin 

 is trituberculate. The rest of the carinae project outward. 

 Towards the posterior extremity they incline more and more 

 backward until in the last segment they unite behind, forming a 

 pointed marginally 5-tuberculate plate overhanging the anal 

 plates. Dorsally there are two rows of bi- and tri-tuberculated 

 carinae that increase in height posteriorly. In the antepenulti 

 mate segment the two rows converge, and in the penultimate 

 segment become united, so that this and the last segment have a 

 single crest-like process projecting considerably backward. Be 

 tween the dorsal and. the lateral carinae are two rows of simple 

 tubercles, the inner row of which is most prominent. 



The repuguatorial pores are distributed very peculiarly, occur 

 ring in the fifth, seventh, tenth, thirteenth, and fifteenth segments 

 only. The pores are at the end of small white, conical, black- 

 tipped stalks, arising from the 1 posterior half of the outer carinal 

 margin. 



As in other polyclesmids the first segment is apodous. 



The general appearance, size, and the pore-bearing stalks sug 

 gest that the genus should be placed in the family Stylodesmidae, 

 erected by Cook for several Liberian diplopods. 'The pore for 

 mula, however, and non-concealed character of the last segment 

 are different, and at once preclude the possibility of the animal's 

 being classed as one of the Stylodesmidae. Inasmuch as the pore 

 formula is unique, and separates the genus from all other de 

 scribed forms, it is proposed that it be considered the type of a 

 new family, Decaporodesmidae, as well as of a new genus and 

 species, Dccaporodesmus motzoranginis. 



Habitat, Motzorango, Mexico. 



