GENERALITIES^ IIOLOTHURIIDAD. 
Ech. 3 
24. Tiieel, H.. Note sur quelques Holothuries desmers de la Nouvelle 
. Zemble. N. Act. Ups. (3) vol. extraord. (1877), 18 pp., 2 pis. 
25. Thomson, C. Wyvillr. On the Structure and Relations of the 
genus llolopus. P. R. Soc. Edinb. 1876-77, pp. 405-410. 
26. Troschel, F. H. Rhahdocidaris recens^ sp. n. Arch. f. Nat. xliii. 
pp. 127-134, pi. viii. Nachtragliche Bemerkung ; tom. cit. p. 127. 
(Additional remarks : Yerh. Ver. Rheinl. xxxiv., SB. niederrhein. 
Ges. 1877, pp. 334 & 335.) 
Generalities. 
Fol’s researches (6) on the primordial changes in the egg, especially 
that of Asterias, tend to show that the disappearance of the “germinal 
vesicle ” and “ spot ” and the expulsion of the “ polar globules ” are merely 
phenomena of the maturation of the ovule, independent of the fecundation ; 
that the “ female pronucleus ” has no genetic connection with the “ nucleo- 
lus” of the egg and only a remote one with the “nucleus” (germinal vesicle); 
and that the spermatozoid exerts upon the vitelline material not only an 
attraction of contact, but even attraction at a distance. The immediate 
consequence of the fecundation, during which the body of the spermato- 
zoon flows into the vitellus, is the differentiation of a true vitelline mem- 
brane, preventing the other spermatozoa, which are perhaps only a few 
seconds later than the first, from penetrating. The “ male pronucleus,” 
through the fusion o£ which with the female one the first “nucleus” of 
the egg owes its origin, is not formed exclusively from the body of the 
spermatozoid, but probably by its fusion with vitelline elements. The 
fecundation of immature ova results in their penetration by a largo 
number of spermatozoa, the consequence of which appears to be the 
formation of several “ amphiasters,” irregular segmentation, monstrous 
larvos, &c. Hertwig’s results (9) are on the whole in good accordance 
with Fol’s ; this author also refutes the objections raised by Giard (8) and 
Perez (18). 
Duncan & Sladen (5) have recorded 20 species collected during the 
last polar expedition, among which may bo noticed Solaster furcifer 
and Antcdon celtmis, not previously known from higher latitudes, 
and a new Asterias. In Marenzeller’s report (16) 17 species are 
noticed, among which are Antedon celiicus and sars^^ Corethraster 
hispidus, W. T., and a new Haplodactyla. The Echinodermaia of 
the deep-sea are often alluded to in Wyville Thomson’s “ The Atlantic” 
(vide infra). The observations on reproduction and growth, recorded in 
Zool. Rec. xiii., are reproduced, i. pp. 215-244; on their frequence and 
occurrence at the greatest depths, &c., ii. pp. 346-348. 
HoLOTHURIIDiE. 
Haplodactyla arcticay sp. n., Marenzeller (16), p. 29, pi. iv. fig. 1 (78^ 58 
N. lat., 260 metres). The anatomy is also worked out. It is described 
as having 15 cylindrical tentacles. H. ooliticay Pourt., and Molpadia 
