BY E. J. GODDARD. 65 



Order BhynchobdelliDvE. 

 Suborder Ichthyobdellid.*:. Suborder Glossiphoniid.e. 



Genus. 



Annuli 

 in Somite. 



Branchellion 3 



Ozobranclms { ^.^^eiy 4 



PonfobdfUa 3 or 4 



Ciistohranchiis 7 



Trachylohdella ;■», 6 



CallohdMa 6 



Piscicola 1'2, 14 



Semilageiieta 3 



Genus. 



Annuli in 



Somite. 



(j1o>i>iipli.on ia 3 



Helobdella 3 



Hcementeria \ '- . \ 



{ o ventral. 



Plarobdella 3 



ffe7niclep/<i>! 3 



M icrobdeUit 2 



Order Arhynchobdellid.e. 

 Suborder Hkrpobdellid.e. Suborder Gnathobdellid.?;. 



In only four genera of the Ilirudinea is the complete .somite 



known to consist of four annuli. In this category fall species of 



Pontohdella, Ozohranchun Margoi, Orobdella Whitinani, and 



Philcemon pungens. lu all these forms it appears that the 



sensory annulus is represente(i by the third ring. This fact is of 



some special interest in the study of the order of development of 



the annuli from the uniannulate to the multiannulate condition 



of the somite, especially as it bears directly on the question of 

 5 



