146 OLIGOCHAETA 



all Oligochaeta produce cocoons. The number of genera and species, however, in 

 which they are known is very limited. Among the aquatic families of this country 

 cocoons have been generally found ; the only exception up to the present is the 

 genus Aeolosoma. In this genus cocoons were described by MA.GGI; but more 

 recently I adduced evidence to show that these so-called cocoons were not really 

 organs comparable to the cocoons of other Oligochaeta, but were cysts of a temporary 

 nature, in which the adult worm enveloped itself; my observations were confirmed 

 by VEJDOVSKY (2). Among earthworms cocoons are known in but few forms. 

 For several species of Lumbricus, Allolobopkora, and Allurus they have been 

 described, especially by DUGES and VEJDOVSKY (9). The cocoon of Criodrilus is 

 also known. It is among the exotic genera that our information is most defective. 

 I described some years ago the large cocoons of the huge Megascolex coeruleus of 

 Ceylon; more recently FLETCHER has referred to the cocoons of a few Cryptodrilids, 

 while SPENCEK (1) and VEJDOVSKY (4) have described and figured that of Mega- 

 scolides australis. I have dealt with the cocoons of Octochaetus multiporus, and 

 have seen also the cocoons of Acanthodrilus annectens. BENHAM (7) has given an 

 account of the cocoon of his new genus Sparganophilus ; FLETCHER (6) of Megascolex 

 dorsalis. This, I believe, summarizes the scope of our present knowledge. 



In the Lumbricidae 'the shape of the cocoon is only characteristic for a few 

 species,' remarks VEJDOVSKY ; they are oval or barrel-shaped bodies, with a process 

 at either end ; one of the two processes is commonly thinner than the other and is 

 sometimes frayed out into a number of threads. 



In Lumbricus rubellus there is an obvious outer membrane, of a transparent 

 appearance, which is prolonged beyond the end of the thinner process for a distance 

 of lomm. ; this membrane is soft, and minute particles of earth adhere to it; later 

 it gets to be less soft and is, therefore, not so clear. I have found that a double 

 membrane is also characteristic of the cocoons of Octochaetus multiporus. VEJDOVSKY 

 is of opinion that this outer membrane is formed in a different situation from that 

 where the horny inner membrane is formed : the latter is, he thinks, produced, as 

 in the genus Rhynchelmis, from the epidermis of the segments which contain the 

 gonads, the spermathecae, &c. ; the soft membrane he traces to the clitellum, for the 

 reason that worms were found with a mucous layer just thrown off from the 

 clitellum. Direct observation, however, is wanting for the settlement of this point. 

 There is variation in the colour of the cocoon of the Lumbricidae. In Allurus they 

 are of a green colour ; a yellow colour characterizes the cocoons of Allolobophora 

 putra, &c. ; Allolobophora octaedra has milk-white cocoons ; in Lumbricus rubellus 

 a dark brown or blackish tint is observable. The cocoon of Megascolex coeruleus is 



