ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 579 



intestine the neoblasts do not form mesoderm, but collect in an unor- 

 ganized mass at the posterior end of the body. When, during the absence 

 of the intestine, the regeneration of the body-wall at the posterior end 

 of the body does not take place, the ectoderm cells that have been 

 metamorphosed into neoblast-like cells enter the coelom, and together 

 with the neoblasts form a mass of cells in the ventral half of the coelom. 

 Neither the position of the neoblasts nor the area over which the ecto- 

 derm cells are metamorphosed is influenced by inverting the position of 

 the worm's body. The neoblasts are always found about the meta- 

 morphosed ectoderm cells at the posterior end of the body, and it seems 

 probable that the neoblasts have some influence in causing the ectoderm 

 cells in their immediate vicinity to assume a neoblast-like character. 

 The neoblasts can migrate towards the anterior end of the body, but 

 they do not come in contact with the ectoderm at this point, and do not 

 form mesoderm. They are not present at the anterior end of Tubifex or 

 Limnodrilus at levels from which anterior regeneration occurs. They 

 were not found anterior to the tenth somite under any conditions. The 

 secondary mesoderm at the anterior end of the body is formed from the 

 old mesoderm. 



Species of Arenicola in Paris Museum.* — J. H. Ashworth reports 

 on the collection of lob-worms in the Museum of Natural History in 

 Paris. It includes Arenicola marina, A. grubii, A. ecaudata, and A. 

 pusilla. A description is given of the last. 



Body-wall of Leeches.f — L. Hachlov deals in the first instance with 

 Hirudo medicinal is, describing the epidermis, the unicellular glands, the 

 connective-tissue, the pigment-cells, the botryoidal tissue, and the muscu- 

 lature. He also discusses "Bayer's sensory organs " in Olepsine sexoculata. 



New Gephyrean Type.! — F. H. Stewart describes from the Indian 

 Ocean Investigator sicarius g. etsp.n., which seems to be a type of a new 

 order of Gephyrea. The order Investigatoroidea is thus defined : — 

 Gephyrea with anterior terminal mouth and posterior sub-terminal anus, 

 witli a nervous system consisting of dorsal cerebral ganglia and two 

 lateral nerve-cords. Within the phylum, Investigator most closely 

 approaches Priapuloidea, the only important difference being in the 

 nervous system. 



The body is divided into a sausage-shaped trunk, a longer narrower 

 neck, and a globular introvertible head. There are numerous glassy 

 chitinous spines. The hind end of the body is formed by a flatly 

 conical shield. The spines at the edge of the shield are long and spike- 

 like, projecting outwards, but on the surface of the shield they converge 

 on an aperture in the centre. This leads into a gill-chamber containing 

 a bilaterally divided gill. The anus opens on the ventral wall of this 

 chamber. There are two nephridia opening at the edge of the shield. 



Life-history of Diplodiscus temporatus.§ — L. R. Cary has made 

 an experimental study of the life-history of Diplodiscus temporatus Staf- 



* Ann. Sci. Nat., x. (1909) pp. 111-24 (4 figs.). 



+ Zool. Jahrb., xxix. (1910) pp. 449-84 (3 pis. and 3 figs.). 



t Memoirs Indian Museum, i. No. 4 (1909) pp. 283-93 (1 pi. and 3 figs.). 



§ Zool. Jahrb., xxviii. (1909) pp. 595-659 (4 pis.). 



