462 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of Eckinoids, five of Holothuroids, including Molpadia dendyi sp. n. Of 

 much interest is the record of Odontotaster grayi, previously recorded 

 from Tierra del Fuego — an illustration of the subantarctic nature of 

 much of the New Zealand marine fauna. Some of the other records 

 have a similar interest. 



Holothuria forskali in Scottish Waters.* — James Ritchie records 

 the occurrence of this Holothurian, the " cotton-spinner," from Mallaig, 

 towards the southern end of the Sound of Sleat. He quotes from an old 

 description by Peach an account of the way the irritated animal ejects a 

 bunch of threads, which breaks up into a large mass of filaments finer 

 than the finest sewing-cotton, quite effective in entangling even a crab. 



Ccelentera. 



Development of Nematocysts.t — Ludwig Will has studied this in 

 Hydra, Syncoryne, Physalia, etc., and distinguishes two chief stages. 

 In the first, the secretion-phase, two kinds of secreted material are 

 formed in the plasma of the formative cell ; in the second, the differ- 

 entiation-phase, the complicated structure of the nematocyst is formed 

 out of the homogeneous secreted material. The primordium of the 

 stilet is formed first, then the coils of the lasso, and so on, all from the 

 arrangement of the alveolar structure that appears in the homogeneous 

 secreted substance. 



Study of Stinging-cells. :j: — Otto Toppe has made a detailed study 

 of the minute structure of the stinging-cells in Hydra, Vellella, Tubu- 

 laria, Pennaria, Syncoryne, Physalia, Pelagia, and Ohndias. He uses the 

 characters of the stinging-cells to distinguish the four species of Hydra. 

 The process of explosion is discussed at some length, and Toppe's con- 

 clusion is that it is begun and in some measure continued by muscular 

 contraction, but that it is completed by the penetration of water into 

 the interior of the capsule, as Iwanzoff and Schneider have maintained. 



Antarctic Medusae. § — E. T. Browne reports on a collection of 

 seventeen species of Hydromedusa3 and Scyphomedusre in almost as 

 many genera. All are either new species, or have been recently described 

 as new species from the Antarctic. Among the anatomical results we 

 may note two. The interior of the stomach of the Hydromedusan 

 genus Koellikeria is covered with minute endodermal papilla?, but 

 whether these have the same function as the gastric filaments of Scypho- 

 medusse is unknown. In a new species of Sibogita, the mature gonads, 

 which are in the ctodermal pouch, intrude upon the stomach, which ceases 

 to be a stomach, and is filled up with endoderm and gonads. Some of 

 the author's general conclusions are noteworthy : there is no proof that 

 a single species of Medusa is common to Arctic and Antarctic ; there is 

 definite evidence of primitiveness in some Antarctic species, as if the 

 cold slowed evolutionary change ; it is doubtful whether there are any 

 " deep sea " Medusas in the strict sense. 



* Ann. Scot. Nat. Hist. (Jan. 1910) pp. 11-12. 

 t SB. Nat. Ges. Rostock, ii. (1910) 42 pp. (G figs.). 

 \ Zool. Jahrb., xxix. (1910) pp. 190-280 (4 pis.). 



§ National Antarctic Exped. (Nat. Hist.) v. (1910) Ccelentera, No. 5, pp. 1-62 

 (7 pis.). 



