HYDROZOA AND CTENOPHOEA. 
Coel. 5 
becomes very dim. Infusion of Cyanea, on the other hand, gives nearly 
the same bands as the blue of Stentor cwruleus. 
40. MetschnikOff, E. Vergleichend-Embryologische Studien, Z. wiss. 
Zool. xxxvi. pp. 433-444. 
The author has previously shown (Z. wiss. Zool. 1874, p. 17) that the 
endoderm in the Geryonida forms by a process of delamination, and now 
confirms this, giving a fuller series of figures ; but he adds nothing to 
our knowledge of the later development. The somewhat degenerate 
development of Cunina, which is found parasitic in the marginal canal of 
Carmarina, is also described. 
41. Moseley, H. N. Report on certain Hydroid, Alcyonarian, and 
Madreporarian Corals procured during the Voyage of H.M.S. 
‘ Challenger.’ Rep. Sci. Results Challenger, Zool. ii. 248 pp., 32 pis. 
[See Zool. Rec. xv. Ccel. pp. 17-19.] 
42. Natiiorst, a. C. Om Aftryck of Medusor i Sveriges Kambriska 
Lager. Sv. Ak. Handl. xix. 
43. Ridley, S. O. Ccelenterata from the Straits of Magellan, &c. 
P. Z. S. 1881, pp. 101-107. 
7 species of Hy droids are described : — Lafocea dumosa, Eudendrium 
arhusculum, Salecium delicatulum^ Sertularella johnstoni, S. polyzonias, 
Sertularia trispinosa^ S. fusiformis. The genus Lahiopora, hitherto 
known by a single dried specimen, L. antarctica, receives a new species, 
L. moseleyi. 
44. Romanes, G. J. Medusm and Hydroid Polyps living in Fresh Water. 
Q. J. Micr. Sci. xxi. pp. 162 & 1G3. 
45. . Concluding Remarks on the Locomotor System of Medusa’. 
Phil. Tr. clxxi. [1880], pp. 161-202. 
Artificial rhythm may be brought about in various species of both 
covered-eyed and naked-eyed Medusm, but in some electrical and in 
others chemical stimulation is most effective, though in all cases the stimu- 
lation must be constant and only of minimal, or very slightly more than 
minimal, intensity. Eventually exhaustion produces irregularity and 
cessation of the rhythm, and prolonged rest is required before any rhythm 
is again obtained. Increasing the strength of the current within certain 
limits, increases the rate of the rhythm. A theory of the part played by 
exhaustion in the production of artificial rhythm is put forward, and 
conclusions drawn thence as to the part it may play in the production 
of a natural rhythm. The other experiments are based upon the method 
of “ sections.” 
46. Varenne, a. de. Sur I’origine des sperm atozoides chez les Hydraires. 
C. R. xciii. pp. 1032-1034. 
The types studied are Campanularia Jlexuosa, Gonothyrcea loveniy 
and Podocoryne carnea. The sperm mother-cells arise in these cases in 
the coenosarc, and the gonophore is subsequently fprmed. The sperm 
mother-cells form a mass of smaller cells, and the appearance of these ‘ 
