42 SUMMARY OF CURRENT RESEARCHES RELATING TO 



from the epidermis, or, in other words, where it is more exposed to the 

 danger of being injured than when more internal in position. 



Annelid Genus Spinther.* — Prof. L. v. Graff gives an account of 

 the polychaetous genus Spinther. After an historical introduction and 

 some general remarks the author gives a full definition of the genus ; 

 the body is elliptical, all the segments except the cephalic and anal have, 

 in addition to a pair of short marginal parapodia, paired dorsal dermal 

 folds, which arise above the parapodia and extend as far as the middle 

 line of the strongly curved back. Both the lamellae and the parapodia 

 radiate from the foci of the ellipse. At the base of the dorsal tentacle 

 are four small eyes covered by integument. The upper free surface of 

 the dorsal lamellae is supported by chitinous spines which are ordinarily 

 arranged in two rows, but the tips only of these spines project. The 

 two ventral nerve-cords are widely separated, and have but feeble 

 segmental swellings. The pharynx is tongue-like, muscular, and pro- 

 trusible, with a ventral groove ; there is no maxillary apparatus ; the 

 midgut has paired diverticula, and the hindgut gives off a forwardly 

 directed dorsal caecum. There are no special gills or segmental organs, 

 and the sexes are separate. The worms live on marine sponges to 

 which they attach themselves by their setae. Definitions of the species 

 follow ; of these there are three— Spinther oniscoides, S. miniaceus, and 

 S. arcticus. The second of these is the most widely distributed, and its 

 varieties show relationship sometimes to S. oniscoides, and sometimes to 

 S. arcticus. S. miniaceus must be regarded as the primitive species. Full 

 anatomical details are given. 



The peculiar elliptical form of the body of Spinther (and Euphrosyne), 

 with the radial arrangement of the segments anteriorly and posteriorly, 

 as well as the gradual shortening of the segments and their appendages 

 towards the anal end of the body, are certainly not primary structures ; 

 here, as in the very similar Myzostomida, the radial configuration of the 

 body must be regarded as the consequence of an adaptation to the 

 parasitic fixed mode of life. In both groups the ancestor must be sought 

 for in elongated forms with equally developed somites, but we cannot 

 yet say where this ancestor of Spinther is to be looked for. 



Structure of Serpula.j — Sigr. V. Simonelli has investigated the 

 microscopic structure of Serpula spirulsea Lam., and finds that his results 

 furnish new evidence in favour of that separation of this species which 

 Defrance (1847) long since suggested. He describes the complex struc- 

 ture of the limy tube, which he succeeded in satisfactorily sectioning, 

 and shows how it differs from other Annelids. Nor can the species be 

 ranked beside Vermetus. S. vertebralis and S. heliciformis were also 

 studied, which closely resemble S. spirulsea. It seems at least necessary 

 to drop the title Serpula as applied to these forms, and to revive the 

 generic titles Botularia or Spirulsea. 



B. Nemathelminthes. 



Maturation and Division of Ascaris Ova. J — Prof. J. B. Carnoy laid 

 the results of his observations before a conference of microscopists at 

 Brussels. 



* Zeitschr. f. Wiss. Zool., xlvi. (18S7) pp. 1-66 (9 pis.), 

 f Proc. Verb. Soc. Toscana Sci, Nat., v. (1887) pp. 293-5. 

 X La Cellule, iii. (1887) pp. 225-45. 



