ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 029 



Comparative Age of Recent Crinoid Faunas.* — A. H. Clark con- 

 siders recent Crinoid faunas in their "physiological phylogenetic aspect." 

 Faunas, like individuals, specieB, and genera, pass through a period of 

 youth, of adolescence, of maturity, and of senescence. The Bering Sea 

 Crinoid fauna is the nearest approach to a young fauna that can be 

 found. The Antarctic Crinoid fauna is also very young. The Crinoid 

 fauna of southern Japan is adolescent ; the West Indian Crinoid fauna 

 is approximately mature ; the Australian Crinoid fauna is a perfect 

 example of a senescent fauna, including about fifty species, nearly all 

 of which are remarkable for the grotesque exaggeration of their specific 

 characters. A pathological fauna may resemble a senescent fauna in its 

 general facies ; but in a pathological fauna all the species, beside being 

 aberrant, are excessively variable, which is never the case in a senescent 

 fauna. Pathological faunas occur usually on the limits of faunal areas, 

 e.g., in the southern part of Massachusetts Bay. 



Ccelentera. 



Hexactinise from New South Wales.f — Leonora J. Wilsmore describes 

 Peachia hilli, Phellia browni, and Ph. capitata, three new species. The 

 structure of the new Peachia is described in some detail. Two points 

 may be referred to. There are numerous pores through the body-wall 

 in longitudinal rows in the region of the physa ; there is a powerful en- 

 dodermal muscle-system, and a sphincter. The two Australian species of 

 Phellia are characterized by the unusual strength of the sphincter and 

 its peculiar contraction into two parts. The size and prominence of the 

 acontia are also unusual characteristics. 



Middle Cambrian Medusa.}— C. D. Walcott describes from British 

 Columbia Peytoia nathorsti g. et sp. n., a highly organized Medusa, whose 

 relation to the order Rhizostomas is shown by its discoidal bell without 

 known annular furrow or pedalia, by the lappets on the margin of the 

 bell, by the absence of tentacles, and by the probable presence of adradial 

 arm-like processes at the mouth. 



Development of Lucernarians.§ — W. Wietrzykowski has continued 

 his study, starting with a polyp with four perradial tentacles, and four 

 interradial septa showing primordia of the taeniolar muscles. He follows 

 the appearance of the successive tentacles. 



Notes on Structure and Budding of Limnocnida.|| — C. L. B<»u- 

 lenger has studied some points in the structure of Limnocnida tanganicee, 

 the fresh-water medusoid of Lake Tanganyika. The stinging-cells mi 

 the tentacles are not developed in situ, but in the ectoderm of the 

 "nettle-ring" (a thickened band at the edge of the umbrella). They 

 migrate thence to the tentacular batteries. The "nettle-ring" is to 

 be regarded as the factory and storage-place of these stinging-cells, 



* Amer. Journ. Sci , xxxii. (1911) pp. 127-32. 



t Journ. Linn. Soc. (Zool.) xxxii. (1911) pp. 39-57 (3 pis. and 1 fig.). 



j Smithsonian Misc. Coll., lvii. (1911) No. 3, pp. 55-8 (1 pi.). 



^ Arch. Zool. Exper., vi. (1911) Notes ct Revue, No. 2, pp. xlix-lii (2 figs.). 



|| Quart. Journ. Micr. Sci., lvii. (1911) pp. 83-106 . 1 pi. and 3 figs.). 



