176 MR. F, FINN ON A FUNCTIONAL DUCTUS [Feb. 17, 



are three gizzards, which, like those of Heliodrilus and Hyperiodrilus, 

 are situated at the junction of the intestine and oesophagus ; each 

 gizzard occupies a single segment. These three genera, which 

 belong to Perrier's Intraclitellian group, show that one of the cha- 

 racters made use of to distinguish that group from the Anteclitellians 

 no longer holds. M. Perrier ^ writes : — " Chez les Lombriciens ante- 

 clitelliens que nous avons etudies, le g^sier s'est toujours trouve 

 place en ai-ribre des organes genitaux et de leurs organes accessoires, 

 en arriere aussi des anses contractiles ou coeurs lateraux de I'appareil 

 circulatoire. Dans ces Vers, I'oesophage est d'ailleurs tres-allonge 

 et la ceinture rejetee relativement tres-loin en arriere ; quelquefois 

 presque au milieu du corps. 



" Au contraire, chez tous les Lombriciens intra- ou postclitelliens, 

 le gesier est place en avant des testicules et des ovaires, c'est-a-dire 

 en avant des organes essentiels dela generation. II est egalement en 

 avant des centres d'impulsion du sang, que ce soient des cceurs 

 dorsaux impairs, comrae chez YAnteus, ou des cceurs lateraux, 

 comme chez les autres Lombriciens." Since Dr. Horst has dis- 

 covered " an Intraclitellian earthworm, Glyphidrilus, in which the 

 clitellum occupies the " anteclitellian " position, viz. from segment 

 23-31, it is impossible any longer to retain the group," An tecli- 

 telliens." 



It is clear, from this brief account of the salient features in the 

 structure of Libyodrilus, that it forms a quite new generic type, 

 concerning the particular affinities of which I do not for the present 

 offer any suggestion. 



7. On a Functional Ductus Botalli in Nycticorax violaceus 

 and Dafila spinicauda. By Frank Finn, B.A., late 

 Scholar of Brasenose College, Oxford. (Communicated 

 by F. E. Beddard, F.Z.S., Prosector to the Society.) 



[Eeceived February 17, 1891.] 



In his memoir on the " Development of the Branchial Arches in 

 Birds," published in the Transactions of the Royal Society of 

 London for 1888, Dr. J. Mackay has described and figured an 

 abnormality which he met with in the dissection of a Guillemot 

 {Lomvia troile). This consisted in the existence of " the remains 

 of the dorsal connection between the third and fourth arches upon 

 the right side," "as a distinct cord passing between the common 

 carotid artery and the descending portion of the aortic arch." Dr. 

 Ferdinand Hochstetter also records two obliterated ductus botalli in 

 Aquila ncevia and Circus cineraceus (" Ueber den Ursprung der 

 Arteria subclavia der Vogel," Morph. Jahrb. xvi. p. 484, 1890). 



1 " M6moires pour servir etc.," Nouv. Arch. Mus. t. viii. p. 156. 

 ^ Nederl. Dierk. Vereen. Verslag. op. d. Vergad. v., 26 Oct. 1889. 



