§> 166. THE ANNELIDES. 179 



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

 which may be resrarded as a reservoir of egas. 



From the base of this reservoir, a. narrow spiral canal passes off, 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 

 sheath. A Ductus ejaculaterius 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 defereiu into a varicose tortuous canal, which lies 

 in the midst of a dense cellular tissue. The Yasa 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 Sauguisugae form cocoons in a similar manner ; but they are sur- 

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

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

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

 body at the approach of danger /''* 



1 See Brandt, Mediz. Zool. II. p. 252, Taf. XXIX. five pairs of these organs ; with Haemopis, eight : 

 A. fig. 45, 46; Moquin-Tandon, Monogr. loc. and witli Aulacostomum, twelve (Mo//iiin-Tan- 

 cit. p. 80, PI. I.-III.; Leo, Midler's Arch. 18.35, don, Monogr. loc. cit. PI. III. fig. 8 ; PI. I. fig. 3, 

 p. 424, Taf. XI. fig. 10 (Sansruisu^a, Aulacosto- PI. II. fig. 10). With Nephelis, the arrangement 

 mum, Nephelis, Pontobdella, and Piscicola. is different, there being on each side of the poste- 



Accordiug to the careful researches of Fi/ippi rior part of the body, numerous testicular vesicles 



(Lettera sojjra I'anat. e lo sviluppo delle Clepsiue, united iu a botryoidal manner ; see Moquin-Tan- 



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



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



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



tlie two ovaries of Clepsine and Nephelis, consist 4, e-h. These cocoons are often found as brown 



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 ; 



eggs as they ai'e detached from the ovaries, and pass and Brightwell, Aim. of Nat. Hist. IX. 1842, p. 



them along by peristaltic movements. 11. t 



2 Sanguisuga has nine pairs of testicles {Brandt i See Rayer, loc. cit. PI. X. fig. 10, and MoquiiL- 

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

 The Vasa deferentia of the seven pairs with Pis- {Froriep's neue Not. No. 462, 1842, p. 183), the 

 cicala 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, loc. cit. 1S35, p. 423, 5 See Grube, Untersuch. iiber die Entwick. d. 

 Taf. XI. fig. 10). With Pontobdella, there are Clepsmen, 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 Piscicola, Ley- 



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. 



