5^ 166. THE ANNELIDES. 179 



tral surface. The posterior opening connects with a short muscular canal 

 which may be regarded as a reservoir of eggs. 



From the base of this reservoir, a narrow spiral canal passes oflF, and 

 bifurcating into two oviducts, terminates with two round ovaries. ^^^ 



From the anterior opening, a long filiform penis may be protruded, 

 which, when not erected, lies spirally concealed in a bulbous muscular 

 eheath. A Ductus ejaculatorius extending from the seminal vesicles, opens 

 into each side of this sheath. These seminal vesicles are formed each by a kind 

 of continuation of the vas deferens into a varicose tortuous canal, which lies 

 in the midst of a dense cellular tissue. The Vasa deferentia are narrow, 

 and passing backwards along the sides of the body, receive upon their 

 internal surface the short excretory ducts of the five, nine, or twelve pairs 

 of round isolated testicles, which form a double row near the ventral 

 cord.^-^ 



With many Hirudinei, a portion of the skin is connected with the sexual 

 function. Such is the case with Nephelis, with which numerous cutaneous 

 glands are developed upon the back and belly near the female genital 

 ■opening. The skin soon has a bloated, transparent appearance, so that the 

 animal appears to have a girdle about its anterior extremity. Before the 

 deposition of the eggs, these glands secrete a substance which hardens in 

 water, and surrounds the body of the animal like a horny belt. This belt 

 is filled with a greater or less quantity of eggs ; the animal then withdraws, 

 ■or slips out from it, while its two extremities are closed up by its own 

 elasticity ; but the embryos developed in this egg-capsule are not thereby 

 prevented from making their escape. ^^' 



The Saugulsugae form cocoons in a similar manner ; but they are sur- 

 rounded with a very thick, spongy substance. '■*' The various species of 

 Clepsine form sac-like capsules for their eggs, and which they usually carry 

 about with them, attached under their belly, — shielding them with their 

 J)ody at the approach of danger.'^* 



1 See Brandt, Mediz. Zool. II. p. 252, Taf. XXIX. five pairs of these organs ; witli Hapmopis, eight ; 



A. fig. 45, 46; Moqiihi-Tanilon, Monogr. loc. and with Auiacostomum, twelve {Moquin-Tan- 



<;it. p. 80, PI. I.-III.; Leo, Mutter's Arch. 1835, don, Monogr. loc. cit. PI. III. fig. 8 ; ^1. I. fig. 3, 



J). 424, Taf. XI. fig. 10 {Sanzuisuga, Aulacosto- PI. II. fig. 10). With Neptie/is, the arrangement 



mum, Nep/ietis, Pontobdetta, and Piscicola. is different, there being on each side of the poste- 



According to the careful researches of Fitippi rior part of the body, numerous testicular vesicles 



((Lettera sopra I'anat. e lo sviluppo delle Clepsine, united in a botryoidal manner ; see Moquin-Tan- 



p. 16. Tav. I. fig. 5), Grube (untersuch, üb. d. Ent- don, Monogr. loc. cit. PI. III. fig. 4.* 



-wickl. d. Glepsinen. p. 6, Taf. III. fig. 3), and Fr. 3 See Rayer, Ann. d. Sc. Nat. IV. 1824, PI. X. 



Mutter {Mutter's Arch. 1846, p. 138, Taf. VIII.), fig. 1-6, and Moquin-Tandon, loc. cit. PI. VI. fig. 



the two ovaries of Clepsine and JSephelis, consist 4, e-h. These cocoons are often found as browu 



■of long flexuous cords surrounded by two more or scales, glued to aquatic plants. Piscicola forms 



less long muscular sheaths, which are uninterrupt- similar cocoons, but they never have more than one 



edly continuous into the oviducts ; they receive the egg each ; see Leo, loc. cit. p. 425, Taf. .XI. fig. 6 ; 



«ggs as they are detached from the ovaries, and pass and Brightwell, Amu. of Nat. Hist. IX. 1842, p. 



them along by peristaltic movements. 11. t 



'i Sanguisusa has nine pairs of testicles (Brandt 4 See Ray er, loc. cit. PI. X. fig. 10, and Moquin- 



Med. Zool. II. p. 252, Taf. XXIX. A. fig. 32-44). Tandon, loc. cit. PI. V. According to fVedeke 



"The Vasa deferentia of the seven pairs with Pis- (Froriep's neue Not. No. 452, 1842, p. 183), the 



■cicola are dilated before reaching the two seminal medicinal leech ejects from the mouth as a scum, 



vesicles into two long and very flexuous tubes (Epi- the spongy envelope of these cocoons. 



■didymis, according to Leo, Inc. cit. 1835, p. 423, 5 See Grube, Untersuch, über die Entwick. d. 



Taf. XI. fig. 10). With Pontobdetta, there are Clepsinen, 1844, p. 1. 



* [ ; 166, note 2.] For many valuable details on t [ § 166, note 3.] See, for an histological exami- 



the genitalia of the Hirudinei, see the often-quoted nation of these genital glands in Piscicota, Lrif- 



and valuable works of Leydig, loc. cit. p. 120. It dig, loc. cit. p. 122, Taf. IX. fig. 43, e. 49, a. b. c. 



■contains histological, as well as anatomical results. — Ed. 

 '.According to him, Piscicola has six, and not seven 

 ^Leo) pairs of testicles. — Ed. 



