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 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 ejacidatorius 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 Saiigtiisugae 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 

 ix)dy at the approach of danger/** 



1 See Brandt, Mediz. Zool. II. p. 252, Taf. XXIX. 

 A. fig. 45, 46 ; Moquin-Tandon, Monogr. loc. 

 cit. p. 80, PI. I.-III.; Leo, Milller's Arch. 1835, 

 p. 424, Taf. XI. fig. 10 {Sans;uisuga, Aulacosto- 

 mum, Nephelis, Pontobdella, and Piscicola. 



According to the careful researches of Filippi 

 (Lettera sopra I'anat. e lo sviluppo delle Clepsme, 

 p. le.Tav. I. fig. 5), Grube (Untersuch. ub. d. Ent- 

 wickl. d. Clepsinen. p. 6, Taf. III. fig. 3), and Fr. 

 Muller {Muller's Arch. 1846, p. 138, Taf. VIII.), 

 the two ovaries of Clepsine and Nephelis, consist 

 of long flexuous cords surrounded by two more or 

 less long muscular sheatlis, which are uninterrupt- 

 edly continuous into the oviducts ; they receive the 

 eggs as they are detached from the ovaries, and pass 

 them along by peristaltic movements. 



^ Sanguisuga has nine pairs of testicles {Brandt 

 Med. Zool. II. p. 252, Taf. XXIX. A. fig. 32-44). 

 The yasa deferentia of the seven pah-s with Pis- 

 cicola are dilated before reaching the two seminal 

 vesicles into two long and very flexuous tubes {Epi- 

 didymis, according to Leo, loc. cit. 1835, p. 423, 

 Taf. XI. fig. 10). With Pontobdella, there are 



* [§ 166, note 2.] For many valuable details on 

 the genitalia of the Hirudinei, see the often-quoted 

 and valuable works of Leydig, loc. cit. p. 120. It 

 contains histological, as well as anatomical results. 

 Accordmg to him, Piscicola has six, and not seven 

 (Leo) pairs of testicles. — Ed. 



five pairs of these organs ; with Haemopis, ni^'ni ; 

 and with Aulacostomum, twelve {Moquin-Tan- 

 don, Monogr. loc. cit. PI. III. fig. 8 ; PI. I. fig. 3, 

 PI. II. fig. 10). With Nephelis, the arrangement 

 is different, there being on each side of the poste- 

 rior part of the body, numerous testicular vesicles 

 united in a botryoidal manner ; see Moquin-Tan- 

 don, Monogr. loc. cit. PI. III. fig. 4.* 



3 See Rayer, Ann. d. Sc. Nat. IV. 1824, PI. X. 

 fig. 1-6, and Moquin-Tandon, loc. cit. PI. VI. fig. 

 4, e-h. These cocoons are often found as brown 

 scales, glued to aquatic plants. Piscicola forms 

 similar cocoons, but they never have mere than one 

 egg each ; see Leo, loc. cit. p. 425, Taf. XI. fig. 6 ; 

 and Brightwell, Ann. of Nat. Hist. IX. 1842, p. 

 ll.t 



■4 See Rayer, loc. cit. PI. X. fig. 10, and Moquin- 

 Tandon, loc. cit. PI. V. According to JVedekr 

 {Froriep^s neuc Not. No. 452, 1842, p. 183), the 

 medicinal leech ejects from the mouth as a scum, 

 the spongy envelope of these cocoons. 



5 See Grube, Untersuch. iiber die Entwick. d. 

 Clepsinen, 1844, p. 1. 



t [ § 166, note 3.] See, for an histological exami- 

 nation of these genital glands in Piscicola, Ley- 

 dig, loc. cit. p. 122, Taf. IX.. fig. 43, e. 49, a. b. c. 

 — Ed. 



