[ 206 ] 

 XXXII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



Feb.18. A PAPER was read, entitled " Observations made with 

 -^*- the Invariable Pendulum (Jones's), No. 4, at the Royal 

 Observatory, Cape of Good Hope, for the purpose of determining 

 the Compression of the Earth." By the Rev. Fearon Fellows, 

 astronomer of the Cape Observatory : communicated by the Lords 

 of the Admiralty ; who also communicated a Notice of a Meteor 

 observed at the Cape of Good Hope, Oct. 19, 1829; in a letter 

 from Captain Ronald, assistant-astronomer at the Cape Ob. 

 servatory. 



Read also, A Memoir on the Developement of Functions, by 

 J. Walsh, Esq. 



LINN^AN SOCIETY. 



Feb. 2. — A paper was read, entitled The Natural History of 

 Petrophila, a Lepidopterous genus^ in its larva state inhabiting rivers, 

 and furnished with branchiae. By the Rev. Lansdown Guikling, B.A. 

 F.L.S. &c. 



Mr. Guilding relates that the very singular little moth upon which 

 he establishes this Genus occurs in myriads, in its larva state, on the 

 blocks of basaltic trap that occupy the bed of the river of St. Vincent. 

 Much as it differs in its habits from the majority of Lepidoptera, one 

 European species he considers to agree with it in its ceconomy, and to 

 be perhaps referable to the sub-genus which he would separate from 

 Botys, which, from the variety of forms in which it abounds, appears 

 to him to call for division. The types in Mr. Guilding's cabinet which 

 are most remarkable, and which he incidentally enumerates and 

 describes, are Gen. 1. Chloephila, Spec, lineolata, found in St. Vin- 

 cent's: Gen. 2. Kamptoptera, Spec, fuscescens, rare, in St. Vincent's : 

 Gen. 3. Phakellura, Spec, hyalinata (Fabr. Ent. Syst. ii. 2. 213?) 

 abundant in the Antilles. 



It is the Botys stratiotalis (Kirby and Spence, iv. 56, 74.) in which 

 Mr. Guilding finds so close a resemblance to his Petrophila in many 

 respects, that he is persuaded of their near affinity, although there is 

 a trifling difference in the pupal spiracula and in the shape of the 

 branchiae. 



The larva obtaining its food on the rocks in the stream, forms 

 silken tunnels, under which it moves in safety, without danger of being 

 carried off by the current. When at maturity the larva builds a more 

 compact habitation, which, together with the metamorphosis of the 

 insect, the author minutely describes ; as well as a small Trichopterous 

 insect found in great abundance in its society, and resembling it in 

 ceconomy. 



Mr. Guilding thinks it probable that many of the European Botydce 

 found in fenny places, as B. Lemiiata, samhucaia, &c. approach to 

 the Petrophilae, while those in hedges and gardens sliould remain in a 

 separate genus. His arrangement is as follows:— InsectaLEPinoPTERA: 

 Sect. NocTunxA: Yt\m. Botydae : Gen, Petrophila: Spec. Jluviatilis. 



P. ar- 



