628 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.40. 



0. palicaudatus (Attems), and 0. areatus (Pocock). Other Central 

 American countries are not yet represented in the genus Ortho- 

 morpha, except Costa Rica, with a single species, 0. convexus (Carl). 



Pocock's suggestion that 0. erichsonii is probably a synonym of 

 0. Tclugii is unfortunate. A comparison of the types of the two 

 species at Berlin showed that the gonopods were very different, 

 those of 0. erichsonii having three prongs, somewhat as in 0. tri- 

 ramus, but considerably longer and more nearly equal and parallel, 



Saussure's Polydesmus picteti, the third of the species originally 

 referred by that author to the typical section of his subgenus Para- 

 desmus, is also placed by Pocock as a synonym of Mugii, but may 

 prove to be a distinct species. 



A NEW GENERIC NAME FOR THE HOTHOUSE MILLIPED. 



The complications that attend the application of the generic name 

 Orthomorpha to Central American species should not affect the status 

 of the hothouse milliped. None of the previously applied generic 

 names being available, this species remains to be treated as the type 

 of a new genus, for which the name Oxidus is proposed, in allusion 

 to the repugnatorial secretion of prussic acid. This milliped served 

 as the basis of the first chemical investigation of the nature of the 

 secretion. 



Although the animal is perhaps the most common and widely 

 distributed representative of the whole class Diplopoda, several 

 characters available for generic diagnosis seem to have been over- 

 looked. 



OXIDUS, new genus. 



Genotype. — Fontaria gracilis C. L. Koch, a species widely distrib- 

 uted in the tropics and in hothouses. First described, from a hot- 

 house in Austria. Original habitat unknown, but supposed to be 

 in the East Indies. Present description based on specimens col- 

 lected in greenhouses of the Bureau of Plant Industry, U. S. Depart- 

 ment of Agriculture, Cat. No. 810, U.S.N.M. 



Diagnosis. — Antennae inserted low down and close together; first 

 segment enlarged, second and third segments reduced; posterior 

 subsegments crossed by a deep transverse impression; constriction 

 between the subsegments deep and strongly beaded; lateral carinse 

 strongly margined with a prominent setiferous tubercle near the 

 anterior corner; repugnatorial pores distinctly lateral, behind the 

 middle of the segments, with distinct raised rims ; posterior segments 

 scarcely shortened; last segment with two transverse rows of setifer- 

 ous tubercles, the apex with two large rounded, nonsetiferous 

 tubercles; sterna with median and transverse impressions and a 

 broadly conic tubercle at the base of each leg; spiracles with expanded 



