IGG Miscellaneous. 



tile plates, which serve sometimes to push the animal forwards, 

 sometimes for attachment. A.t the base of the mouth- tube com- 

 mences the narrow oesophagus, which traverses the nervous centre, 

 and immediately after passing through this becomes widened into 

 the gastro-intestirial tube. Pyriform glandular organs are appended 

 to the narrow rectum. On each side of the nervous centre are the 

 salivary glands, conglomerated unicellular glands. The sexual 

 organs are unpaired. The sexual apertures are situated immedi- 

 ately behind the last pair of legs. In the male the sexiial aperture 

 appears as a fissure surrounded by swollen margins and with a sup- 

 porting plate ; in the female it is closed by a superior and an 

 inferior opercular plate. The eggs and spermatoblast are developed 

 from a single germinal layer. In the male animal this is sharply 

 separated from the ducts and has a cylindrical form. Before the 

 germinal layer there is a spherical dilatation of the seminal duct 

 lined with glandular epithelium. The sperm-cells are very small, 

 rounded cells. On each side of the female sexual aperture opens a 

 small glandular organ (seminal poTich ?). The rudiments of the 

 sexual organs appear in the larvfe at first as solid cylindrical cell- 

 bodies, the development of which has proceeded so far before the 

 last moult that it is already possible to distinguish the sexes. The 

 nervous centre is represented by a comparatively large, cylindrical 

 ganglion ; from its anterior part issue eight, and from its posterior 

 part two nerves. To the present time the Gall-mites of twenty-four 

 species have been closely investigated. On Garpinus I have found 

 forms the abdomen of which is covered dorsally with shield-shaped 

 half-rings. On Populiis nigra Herr P. Olschar collected deformed 

 buds exactly like those of P. tremula, and which, I believe, have not 

 yet been described. — Anzeiger Acad. Wiss. Wien, 18th November, 

 1886, p. 220. 



On the Conodonts. By MM. J. V. Rohon and K. A. vox Zittel. 



The curious minute fossils originally described by Pander under 

 the name of Conodonts, and which he supposed to be the teeth of 

 cartilaginous fishes of Silurian times, have been referred by subse- 

 quent authors to various types of organisms. They have been 

 regarded as fragments of crustaceans, as the teeth of fishes allied to 

 Myxine and Petromyzon, and as spines aud teeth of naked Mollusca 

 and Annelids. Dr. Hinde, who described many forms of these 

 fossils from Silurian and later rocks, subsequently identified some of 

 Pander's species with Annelid jaws. 



The authors have discussed the question of the true nature of 

 these problematical little fossils in considerable detail, and have 

 described and figured their minute structure as made out by micro- 

 scopical examination of thin sections, and summarize the results of 

 their investigations in the following words : — "■All the forms consist 

 of parallel-laxjered conical lamince, arranged one over the other, and 

 u'hich are sometimes traversed hy fine radial canals." They then 

 proceed to a comparison of the structures recognized by them with 

 those displayed by the various recent objects with which the Conodonta 



