Invertebrata, Zoological Collections. 877 



also remarked this organ, and Home has given very elegant figures of it in 

 the Philosophical Transactions. Modern authors have discovered two of 

 these organs, and M. Morren remarks that they are very irregularly deve- 

 loped ; in general, they are found on the thirty-second or thirty-eighth ring, 

 and their position is frequently alternate, like that of the generative papillae. 

 They are only found well developed at the breeding season, so that there is 

 little doubt that they are connected with reproduction ; the Belgian anato- 

 mist, however, could not discover any channel of communication between 

 this generative appcTidage and the interior of the body. 



The anal opening is formed of several rings, the functions of which can 

 only be comprehended after the examination of the muscles. 



Hitherto, longitudinal muscles only, to the number of two or four, have 

 been mentioned in the Lumbricus ; but the researches of M. Cams on the 

 leech, have led M. Morren to examine if in earthworms the muscular system 

 was not more highly developed than commonly believed. Besides the 

 muscles discovered by M. Cuvier, to whom we owe our first information on 

 this system in the genus Lumbricus, there are evidently transverse and 

 oblique muscles for each ring. The bristles have, moreover, proper retract- 

 ing and protruding muscles, as had already been shewn by the illustrious 

 author of the Rdgne Animal. The mouth has several proper muscles, among 

 which must be distinguished the constrictor, the proper muscle of the upper 

 lip, the levator and depressor ; and, for the lower lip, the proper and the 

 retracting muscle. The anus has two muscles, the radiated and the 

 sphincter. There are in all 772 muscles in this little animal. 



In the Legons d'Anatomie Comparee, mention is made of only a single pair 

 of nerves, which proceed from each ganglion ; but M. Carus, and, more 

 recently, M. Roth, in an excellent dissertation on the nervous system of 

 invertebrated animals, and Sir Everard Home, have shewn that the nervous 

 system is more complex in this animal than was supposed. M. Morren has 

 verified these observations, and added new ones. The brain and oesophageal 

 circle give off cervical, pharyngeal, labial, and oesophageal nerves. At each 

 ganglion of the great cord there is a pair of nerves on each side, and between 

 the ganglions there is another pair. Some of the nerves are annular, others 

 interannular. 



The organs of sense are few; the skin is simple, — it is a translucid 

 epidermis, having metallic colours in several cases, very easily detached from 

 the subjacent muscular layer ; a coloured mucous tissue occasions a brown 

 line on the back. The absorption of odorous molecules is effected by the 

 whole body ; taste is probably very distinct ; hearing and vision are entirely 

 w^anting. 



Among the organs of the digestive apparatus, we remark the pharynx in 

 front, in some a salivary gland ; the oesophagus, which has frequently very 

 remarkable glandular ducts, and, opposite the ovaries, two pairs of peculiar 

 glands disposed like a cross, and very little understood. Moreover, in some 

 worms there is found an elongated gland, white, and fusiform, which 

 occupies the anterior part of the oesophagus ; this may be presumed to be 

 the true salivary gland. The gizzard is well developed, and varies much in 

 form ; it leads to the stomach, which is very muscular, and receives a great 

 number of blood-vessels. The intestine has thick walls, and is composed of 

 two tunics, the outermost of which is covered by papillae, corresponding to 

 the liver, which has very many lobes. According to Home, there are 

 openings in each lobe, leading to the cavity of what is called intestinum in 

 intestino ; but M. Morren could see nothing of the kind. Nothing certain 

 is known of this last organ, to which the author gives the name of 

 typhhsole. MM. Home and Carus attribute to it the strange function of 

 serving as a conduit for the escape of the young ; and the former natu- 

 ralist thinks that it furnishes their nourishment. Nothing, however, can 

 be more erroneous; repeated observations induce M. Morren to think 



VOL. III. 3 B 



