1892.] Zoology. 521 



species in a small vivarium, and on examination he found under a bit 

 of rotten wood some twelve or fifteen eggs which closely resembled 

 those taken from the oviducts of other females except that the chorion 

 was exquisitely sculptured. This evidence is relative, not absolute, 

 as will readily be seen. 



North American Thysanures. 1 — Alex. Macgillivray catalogues 

 the known species of North American Thysanura, enumerating 74 

 species. The list leads off with the three species of Scolopendrella. 



Stridulation in Lepidoptera. — At the meeting of March 1, 

 1892, of the Zoological Society of London, Mr. G. F. Hampson read a 

 paper on stridulation in certain Lepidoptera. The author attributed 

 the clicking sound described by Darwin as produced by various 

 species of the South American genus Angerona, and confirmed by 

 Wallace and other observers, to the presence of a pair of strong corne- 

 ous hooks with spatulate ends attached to the inner margin of the fore 

 wings close to the base, and surrounded by a membranous sac which 

 acts as a sounding board. An account was given of a similar sound 

 produced by the males of a Burmese moth of the family Agaristidse 

 and of a buzzing sound in an allied Australian form, both of which 

 have a patch of ribbed hyaline membrane below the costa of the fore 

 wing. The sound was attributed to the friction of spines, attached, in 

 the former to the first pair of legs, in the latter to the second pair, 

 upon the ribbed membrane. A description was then given of the 

 transformation of the costal half of the hind wing in the Noctuid 

 genus Patula into a large scent gland, and of the manner in which 

 this had distorted the neuration.— Zool. Anz., No. 387. 



A New Compound Ascidian.— W. Garstang describes 2 under 

 the name Archidistoma, a new genus of the Ascidian family Dis- 

 toniidse which is of especial interest since " it exhibits the first stage in 

 the evolution of the coenobitic type of colony from the Social Ascidian 

 type, in which the zooids are entirely free and irregularly placed ; in 

 Archidistoma aggregatim the clumps of zooids (primitive ccenobia) 

 have no common cloaca, but the cloacas of the individuals are usually 

 situated towards the center of the groups. The second stage is 

 exhibited in such a compound Ascidian as Synoicum turgens or Cir- 

 cinalium conerescens, in which each of the isolated clumps of zooids 

 possesses a common central cloaca." 



'Can. Entomol., xxiii, 267, 1891. 



