1899.] ON TWO EARTHAVORMS. 803 



fig. 2, A & B), but it does not reach the margin of the pallium. 

 It is, however, always very near to reaching this margin ; and on 

 one side of one brain it appeared actually to do so through 

 becoming confluent with another fissure of short length. 



On the mesial surface of the brain a single fissure (fig. 5, E) is 

 very plain anteriorly, which curves round the anterior end of the 

 corpus callosum. This is the limbic fissure of Broca, splenial of 

 other authors, and, I presume, calloso-marginal of still others. A 

 very interesting little fissure .was observable in the best preserved 

 of the two brains which I bisected longitudinally. This is shown 

 in fig. 5. At the end of the hemisphere is a short vertical fissure 

 (A, B, C) and a shorter one still behind this, and a more faintly 

 marked one in front. It is of course an obvious suggestion that 

 they are the parieto-occipital and calcarine respectively. 



9. Notes upon two Earthwornas, Perich<Bta biserialis and 

 Trichoch(Bta hesperidum. By Frank E. Beddard, 

 M.A., F.R.S., and Sophie M. Fedabb. 



[Keceived June 6, 1899.] 



The first of these species (PericJiceta biserialis) was originally 

 instituted more than twenty years ago by M. Perrier\ whose 

 description, however, was only in the nature of a " preliminary 

 communication." The two matters to which he referred, viz. the 

 disposition of the genital papillse and the enlarged setae on either 

 side of the ventral median line, were sufficient at that time to 

 fully differentiate the species. 



Subsequently one of us received and described ^ some specimens 

 of an earthworm belonging to this same genus also from the Philip- 

 pine Islands ; they were referred to the same species, though the 

 entire absence of spermathecse was noted. Upon this latter point 

 Perrier made no observations. It was therefore concluded that 

 it would be better to regard the worms described as being of a 

 different species. In the ' Monograph of the Oligochaeta ' 

 therefore they were described under the name of PericJiceta acystis. 

 Since then Michaelsen ^ has re-described PericTut'ta hiserialis very 

 fully, and more recently still Dr. Horst ■*. 



Dr. Horst, whose observations where published after ours were 

 made, examined eight mature worms from Paramaribo in Dutch 

 Surinam : " of these two have four pairs of copulatory papillae on 



> " Sur les Vers de terre des Philippines et de la Oochinchine," Comptes 

 Eendus. 1875, p. 1043. 



2 P. E. Beddard, "Observations upon an American Species of Perichceta, &e. " 

 P. Z. S. 1890, p. 63. 



' " Die Terrieolen des madagassischen Inselgebiets," Abb. Senck. nat. Gas. 

 xxxi. (1897) p. 226. 



* " On the Variability of Characters in Perichaetidse," Notes Leyd. Mas. xx, 

 p. 201. 



