INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 433 



of accessory jaws. The species are cephaloptera of Busch, draco of 

 Krohn, gallica of Pagenstecber, and hatziana of Giard. 



The author then deals with the Nemertinea, of wliich eighteen 

 species are found at Madeira ; Cerebratulus Macintoshii, G. Hubrechti, 

 and Tetrastemma quadriseriatum are new. 



Nine Appendicularise were also found, and of these OiJcopleura 

 velifera and 0. magna are new ; the latter has a body of 8 mm. and a 

 tail of 8-10 mm. long in the largest forms. 



Anatomy of the Leech* — Professor Lankester gives the results 

 of a very minute investigation into the histology of the epidermis, 

 connective tissue, blood-vessels, and other parts of Eirudo officinalis, 

 which supplement what has been already written by Leydig and 

 others. 



The epidermis is a unilaminar series of simply cylindrical cells, 

 producing a separable cuticle on the surface ; branches of coloured 

 connective-tissue cells sometimes appear between them. It is noticed 

 for the first time that fine blood-vessels also penetrate the epidermis, 

 and run horizontally among its cylindrical cells, in all parts except 

 the extremities of the body — an arrangement doubtless effecting a cuta- 

 neous respiration. This also occurs in the clitellus of the earthworm. 



The epidermis also contains isolated gland cells, buried deep in 

 the body walls, with ducts rising between the epidermic cells ; they 

 are surface glands, not connected with the brown subjacent tissue, as 

 Leydig states, and as they resemble the salivary glands, they are 

 probably homologous in origin with these. 



The connective tissue is not always to be distinguished from the walls 

 of the blood-vessels. One variety, forming the most massive tracts, is 

 slightly fibrillated, and contains numerous oblong, finely-branched cor- 

 puscles, which are coarsely granulated by highly refracting particles in 

 the older forms. A second variety is formed of ramifying fibres, generally 

 with brownish granules, beset with protoj)lasmic corpuscles at intervals : 

 it constitutes an investment to the chief organs, as the lateral blood- 

 vessels, the nephridia, and the body- wall muscles, &c. It is not sharply 

 distinct from the blood-vessels themselves, for these are sometimes 

 merely hollowed fibres of this kind — a fact paralleled by the facts of 

 the development of the blood-vessels in the rat's omentum. The 

 third variety is the brown botryoidal tissue described by Leydi" as a 

 fat-body like that of insects, by Brandt as a liver, and by Leuckart as 

 part of the epidermal glands. It consists of moniliform, tortuous, 

 branched tubes, passing gradually into blood-vessels ; tlie walls are 

 set with dark brownish granular cells, staining deeply with gold and 

 with osmic acid ; it contains the ordinary rod blood, and constitutes 

 in fact, simply a vascular plexus. A similar plexus occurs in tho 

 Oligochaita, and it is, perhaps, most closely allied to tlie vascular 

 yellow tufts on the alimentary canal of Lnmhricus. Possibly the brown 

 cells act both as- a liver and in tlie manufacture of ha;moglobin. 



Bluod-vcssch. — Though tliere is no body cavity with colourless 

 liquid, as in the Chictopoda, yet large spaces do occur between tho 



• ' Zool. Anzcigor,' iii. (1880) p. 85. 



