ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 535 



descendant affected by precocious dorsal atrophy and progressive left 

 hemilateral degeneration gave rise to the Echinoderai stock. 



Eocene Echinoids from Sokoto.* — F. A. Bather describes and dis- 

 cusses the significance of Plesiolampas Sahara, sp.'n., and Hemiaster 

 sudanensis, sp.n., collected by Captain Lelean in Sokoto. The occurrence 

 of Plesiolampas, a genus hitherto unknown outside Sind, suggests a 

 continuous westward extension of the Eocene Indian Ocean ; and this 

 idea is confirmed by an Egyptian fossil of the same age, identified by 

 Gauthier as Plesiolampas. 



Ccelentera. 



Development of Hydromedusse.f — A. Goette has studied the 

 development of the medusoid in a number of free-swimming and sessile 

 forms. His results are remarkably different in a number of points from 

 those of Agassiz. The radial canals arise from the apical portions of 

 the four tamiolge. The circular canal arises neither from an endoderm 

 lamella nor through side continuations of the radial canals. It appears 

 to be formed independently from outgrowths from the tamioke. The 

 cavity of the bell arises from four radial furrows of the endoderm sepa- 

 rated by the four tamiolre. The ova, in Podocoryne, arise from the 

 ectoderm of the polyps ; in Syncoryne and Bougainvillea from the endo- 

 derm of the bud. The male sexual cells in all the three genera probably 

 have their origin in the outer ectoderm. Only in Dendroclava does the 

 ectoderm of the manubrium appear to be the germinal region, and here 

 not exclusively, since the sub-umbrellar flaps beyond the manubrium 

 likewise give rise to germinal cells. 



Solenocaulon.f — Martin Janower does not agree with Hickson in 

 slumping Solenocaulon tortuosum Gray, Sol. grayi Studer, and Sol. tubn- 

 losum Genth into one species, Sol. tortuosum Gray, with a widened 

 diagnosis. He maintains that these are three good species, to which 

 must be added Sol. (Leucoella) cervicorne Gray. A general discussion 

 of the genus follows. 



Anatomy of Cerianthus Borealis.§— J. S. Kingsley gives some 

 account of this form. It is distinguished from related species in being 

 hermaphrodite. It differs from 0. membranaceus and G. lloycli in the 

 great extension of its septa, five pairs reaching to the aboral pole. The 

 larger and more prominent siphonoglyph in Cerianthus is homologous 

 with the single groove in Halcampa, and hence should be termed sulcus 

 and not sulculus as maintained by Bourne. 



Studies in Anthozoa.[| — 0. Carlgren has investigated the develop- 

 ment of the first twelve tentacles in Peachia, Cribrina (Buuodes), etc. 

 At the eighth tentacle stage in these forms there are only four which are 

 homologous to each other. These are the two directive, and the two 

 which lie on each side of the dorsal directive tentacles ; the four others 



* Geol. Mag. Decade V., i. No. 7(1901) pp. 292-304 (1 pi.). 



t Zool. Anzeig., xxvii. (1904) pp. 473-5. 



X Kevue Suisse Zool., xii. (1904) pp. 495-538 (2 pis.). 



§ Tufts College Studies, No. 8 (1901) pp. 345-61. 



|| Zool. Anzeig., xxvii. (1904) pp. 531-49. 



