172 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. 



Perichceta 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 OP THE PLATES. 



Plate TX. 



Fig. 1. PerichcBta morrisi. Nat. size. 



2. Perichceta dyeri. Nat. size. 



3. Perickcgta sinensis. Nat. size. 



4. PericluBta sumatrana (?). Nat. size. 



5. G-enital segments of Perickcgta sinensis. J, oviducal pore; ,^, atrial 



pore ; p, genital papilla?. The segments are numbered, those of elitel- 

 lum in roman numerals. 



6. 7. Genital .segments of Pericheia barbadensis, two yarieties ; letters 



as above. 

 8. Genital segments of Pericticsta dyeri ; letters as above. 



Plate X. 



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

 septal glands. B.V., dorsal vessel; hit., intestine; S2)t., inter- 

 segmental septum ; gl., septal glands. 



2. Pericha-fa sinensis, mulberry-shaped glands {p.g.) corresponding to 



papillae. 



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



condition. 



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



sp., spermatheca ; cl., diverticulum. 



5. Perichceta mauritiana. jS/^z"., septum between segments xii./xiii. ; Spt.', 



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

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



6. Perichceta mauritiana. iV., nerve-cord ; v.d., vas deferens; at., mus- 



cular part of atrium ; p.g., glands corresponding to papillae. 



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



