1/2 ON WORMS OF THE GENUS PERICH.ETA. [Feb. 16, 



they fuse with the larger tube, and all these open by a common 

 orifice. 



Traced in the reverse direction, one of the two smaller tubes was 

 found to communicate with a separate lobe of the branched atrium. 

 Whether this was or was not the case with the second of the two 

 smaller tubes, I am not able to say. 



These facts are of interest in relation to the structure of the 

 terminal portion of the male efferent apparatus in Perichceta 

 ceylonensis, a species which I described some years ago. 



PerichcBta ceylonensis differs from all other species of the genus 

 in possessing two glandular bodies on each side in the xviiith seg- 

 ment. One of these is a lobed atrium like that of Perichceta in 

 general, but with a straight instead of a curved muscular duct ; the 

 other is a tubular gland like the atria of Acanthodrilus. Unfortu- 

 nately I have not been able to ascertain with which of these two 

 glandular appendages the vasa deferentia communicate. 



It seems to me that in this Perichceta there is a commencing 

 separation of each atrium into two halves which culminates in 

 Perichceta ceylonensis. 



EXPLANATION OF THE PLATES. 



Plate IX. 



Pig. L PerichcBfa morrisi. Nat. size. 



2. PerichcBta clyeri. Nat. size. 



3. Perich(sta sinensis. Nat. size. 



4. Perichceta sttmatrana (?). Nat. size. 



5. Genital segments of PerichcBta sinensis. 5 > ovidaeal pore ; c? , atrial 



pore ; p, genital papilltB. The segments are numbered, tliose of clitel- 

 lum in roman numerals. 



6. 7. G-enital segments of Perichcsta harbadensis, two varieties ; letters 



as above. 

 8. Genital segments of Perichcsta clyeri ; letters as above. 



Plate X. 



Fig. 1. Perichceta dyeri, a portion of intestine and dorsal vessel showing 

 septal glands. B. V., dorsal vessel ; Int., intestine ; Bpt., inter- 

 segmental septum ; gl., septal glands. 



2. Perichceta sinensis, mulberry-shaped glands {p.g.) corresjDonding to 



papillse. 



3. Perichcsta sinensis, a portion of contents of spermatheca in fresh 



condition. 



4. Perichceta sinensis, a spermatheca drawn in the fresh condition. 



sp., spermatheca ; cl., diA'erticulum. 



5. Perichceta mmiritiana. Spt., septum between segments xii./xiii. ; S2of.', 



septum between segments xiii./xiv. ; r.o., receptacula ovorum ; ov., 

 ovary ; /., funnel of od., oviduct. 



6. Perichceta mauriticma. JV,, nerve-cord ; v.d., vas deferens; a^f., mus- 



cular part of atrium ; p-ff., glands corresponding to papillce. 



7. 8. Perichceta sinensis, vascular plexus from spermathecal appendix. 



