324 APPENDIX. 



sixteenth or seventeenth ring, there are two similar but smaller pores 

 on the twenty-seventh or twenty-eighth ring ; and there is a series 

 of very minute pores along the back, one pore to every ring excepting 

 the anterior ones, which are unprovided with it. They are most 

 easily seen near the middle of the body, and especially on that part 

 of it which is between the sixteenth ring and the clitellus. In a 

 large specimen the series consists altogether of from 110 to 120 

 pores, and they are believed to be the entrances to oblong vesicles 

 arranged in a series along the sides, and in which the blood of the 

 worm is aerated. Some good naturalists affirm, however, that the 

 vesicles are merely mucous cysts for furnishing the slimy fluid which 

 lubricates the surface ; and Morren, while he maintains their pul- 

 monary character and use, is also inclined to admit that they may be 

 at the same time mucigerous, and the pores ducts for the outflow of 

 the secretion. 



The Earthworm is hermaphrodite, but the copulation of two indi- 

 viduals is required to impregnate the eggs. 



On the structure of the genus see Duges' essay in the Ann. des 

 Sc. nat. XV. p. 298, &c. 



Mr. Macdonald is confident that the earthworm is the Skolex of 

 Homer. — Zoology of Komer, p. 15. But it has yet to be ascertained 

 whether the common species of Greece is identical with the British 

 species. 



Lumbriciis terrestris (page 58). 



A large species, attaining the length of 8 or even of 10 inches. 

 The portion anterior to the clitellus is cylindrical, forming a very 

 elongated cone, of a dark-brown or bluish-purple colour, paler be- 

 neath ; the posterior portion somewhat flattened, more especially 

 near the end, which is spathulate and crenulate on the sides. The 

 colour of this portion is a sort of yellowish-brown ; and the skin is 

 sufficiently transparent to permit the course of the red vessel that 

 runs down the back, in the medial line, to be seen, as well as the 

 dusky interranea. Head an elongated obtuse cone. On the ring 



Montpellier distinguishes thirty-five species of this genus. He divides it into two 

 sections ; the first distinguished liy having the bristles in pairs, the second by 

 having them placed in the ring at equal distances. Then the number of the ring 

 in which the vulva is perforated serves to divide the sections each into two sub- 

 sections, for the vulva may be either on the sixteenth or on the fourteenth ring. 

 Next, the number of rings in the clitellus serves to bring the species into lesser 

 groups, and the species thus limited are distinguished separately by the number of 

 rings between the first ring of head and the last in the clitellus. On paper this seems 

 an exact and easy method for ascertaining any of the species, but in practice it will 

 be found useless. It is not always easy to count the rings ; nay, generally those 

 of the clitellus cannot be counted ; and there is often a lesser or half ring which 

 may or may not be enumerated, as the whim dictates. We cannot even always 

 certainly fix upon the exact ring in which the vulva is situated. At the season 

 when the organs connected with it are developed, the pore is sometimes so turgid 

 that it presses on the adjacent rings and obscures their lines of separation. 

 Usually the orifice is undistinguishable. As for the number of rings between the 

 head and clitellus, we know that it is uncertain ami variaole in individuals of the 

 same species. 



