1890.] WORMS OF THE GENUS PERICH^TA. 67 



The spermathecce, 4 pairs, present nothing remarkable in their 

 structure ; each is a small pear-shaped pouch with a single small 

 stalked diverticulum. 



The sperm-sacs have a somewhat peculiar structure which is 

 illustrated iu fig. 10. In segments 11 and 12 are a pair of oval 

 sacs ; those of each side of the body are connected with each other, 

 but there is no contact between the sacs of the right and left sides 

 ventrally ; from each of the oval sacs is a small projecting tube- 

 like outgrowth (.r, Plate V. fig. 10), which in the dissected worm 

 appeared to be broken off at its extremity. 1 am inclined therefore 

 to suppose that there is a connection above the intestine between 

 the two sperm-sacs of each segment by means of these outgrowths ; 

 if so, there is a strikina; resemblance in this particular between Peri- 

 ckcBta vaillanti and Dichogaster, in which worm I have fio-ured 

 and described (10) an almost identical arrangement. 



The ovaries are in segment 13, attached to the anterior mesentery 

 of this segment. 



The oviducts are perfectly normal. 



The atrium is again rather unusual in its structure ; as a general 

 rule that portion of it which lies nearest to the external orifice has 

 thickened muscular walls and is curved upou itself like a horseshoe ; 

 its calibre gradually increases towards the external orifice. 



In Perichcela vaillanti the terminal portion of the atrium abruptly 

 widens to form an oval, thick- walled sac, as in P. indica (Horst, 16), 

 into which the thin tube-hke proximal part of the atrium opens. 



The only species with which the present could be confounded is 

 P. modigliani (Rosa, 25) ; but it differs from that species in having 

 no thick mesenteries and apparently in the structure of the sperm- 

 sacs. There is no knowing whether P. vaillanti is the same as 

 P. Juliana (Perrier, 19) ,: the only fact known about the latter 

 species is that it has four pairs of spermathecae. 



List of Memoirs cited. 



1. Baird, W. — Description of a new Species of Earthworm 



(Meffascolex diffrinc/ens), found in North Wales. P. Z. S. 

 1869, p. 40. 



2. Beddard, F. E. — On the Anatomy and Histology of Pleuro- 



ch(Bta moseleyi. Trans. Roy. Soc. Ediub. vol. xxx. (1883), 

 p. 481. 



3. Beddard, F. E. — On the Anatomy and Systematic Position 



of a Gigantic Earthworm {Microchceta rap'pi), from the Cape 

 Colony. Trans. Zool. Soc. vol. xii. pt. 3 (1886), p. 63. 



4. Beddard, F. E. — On the genus Megascolex of Templeton. 



Ann. & Mag. Nat. Hist. May 1884, p. 398. 



5. Beddard, F. E. — Descriptions of some new or httle-known 

 Earthworms, &c. P. Z. S. 1886, p. 298. 



6. Beddard, F. E.— Observations on the Structure and Cha- 

 racters of certain new or little-known Earthworms. Proc. 

 Roy. Soc. Ediub. vol. xiv. p. 156. 



5* 



