August 14, 1890] 



NATURE 



367 



it is most difficult to distinguish the results of crushing 

 and disintegration from actual specific characters ; and 

 even in a formation so little disturbed as the black Triassic 

 shale in which these fishes are entombed, the apparent 

 form of the head and trunk cannot always be relied upon 

 in specific diagnoses. 



Ischypterus is undoubtedly identical with Semionotus, 

 as Dr. Newberry suspects, and is thus represented both 

 in America, Europe, and South Africa. Ichthyologists 

 will doubtless also agree with the systematic position in 

 which the author places the genus. To us, however, it 

 appears that this determination was more conclusively 

 proved by the researches of Dr. Traquair in 1877, when 

 he offered to the Geological Society some detailed re- 

 marks on the osteology of the fish ; and on that occasion 

 the intimate connection between Ischypterus and Semio- 

 notus was equally pointed out. Each of the species is 

 illustrated by at least one figure, and good reason is given 

 for assigning to one of the larger forms the supposed 

 fragment of a Tetragonolepis, brought from Virginia by 

 Lyell. 



Catoptertts and DictyoPyge are retained as distinct 

 genera, in accordance with the usual custom ; and 

 then follow two interesting types which the author him- 

 self has added to the list. A very distinct species of 

 Ptycholepis is described from Durham, Conn., and an 

 equally peculiar species of Acentrophorus is made known 

 from the Chicopee Falls, Mass. Of these genera, the 

 first has hitherto been known chiefly from the English 

 and German Lias, though also rarely obtained from the 

 Austrian Keuper ; while the second has previously been 

 found only in the Permian magnesian limestone and 

 marl slate of Durham, England. 



A preliminary definition of the Coelacanth fish Diplurus 

 longicaudatus was given by Dr. Newberry several years 

 ago ; and the detailed description and figure now pub- 

 lished are a welcome addition to our knowledge of the 

 group to which the fish belongs. The finest specimen is 

 nearly complete, and is only disappointing in the matter 

 of cranial osteology. The largest specimen discovered 

 measured about three feet in length, thus exceeding in 

 size any Coelacanth hitherto met with below the Jurassic. 

 The third portion of the memoir deals with the fossil 

 plants, only seventeen species of which have been brought 

 together. These confirm the views of Saporta as to the 

 infra-lias, or, at most, Keuper, age of the formation, 

 arrived at from a study of the far more important series 

 described by Fontaine in the sixth monograph of the 

 Survey, issued in 1883 ; a series procured from the coal- 

 bearing outliers of the same age in Virginia and Carolina. 

 Of plants common to the Rhaetic of Europe we have 

 Clathropteris platyphylla, Cheirolepis Munsterl, Otoza- 

 mites latior, O. brevifolius, two species of Pachyphyllum 

 hardly separable from P.peregrinum, Equisetum Rogersi, 

 claimed by Saporta to be identical with E. arenaceum, 

 and the doubtful stems well known in many Triassic 

 rocks, sometimes referred to Calamites, but here referred 

 to Equisetum Meriani, Brong., and Schisoneura. 



Among the novelties is Detidrophycus triassicus, a 

 supposed algoid with a cabbage-like leaf destitute of 

 transverse nerves. From the fact that there is in the 

 British Museum an identical structure, from a gritty 

 Tertiary limestone of Mull, which can hardly be organic, 

 NO. 1085, VOL. 42] 



we should question the vegetable nature of this fossil, 

 without, however, being able to suggest any other plausible 

 origin. There is a new Cycadinocarpus, founded on a 

 compressed cycas-looking nut, possibly the fruit of one of 

 the Otozamites ; and the obscure plant, referred to by 

 Fontaine under the misleading name of Bambusium 

 Carolmense, now called Zoperia simplex. Whether, as 

 suggested by the author, this may prove to be an aquatic 

 Monocotyledon — "a kind of gigantic Schollera"— there 

 are no sufficient materials for discussing. It is some- 

 what surprising to find Baiera Miinsteriana located 

 among the Cryptogams, as there are so many forms con- 

 necting it with Ginkgo, all possessing the remarkable 

 twin fibro-vascular bundles in the petiole which result in 

 the symmetrically cleft leaf, that its position is scarcely 

 doubtful. We prefer that the Cycads should precede the 

 Conifers, but in so small an assemblage of species, their 

 want of arrangement is of no great importance. 



A. S. W. AND J. S. G. 



SEA ANEMONES OF THE NORTH ATLANTIC. 

 Den Norske Nordhavs-Expedition, 1 876-1 878. XIX. 



Zoologi : Actinida. Ved D. C. Danielssen. Med 25 



Plader og i Kart. (Christiania : Grondahl and Son's 



Bogtrykkerl, 1890.) 

 A NOTHER part of the General Report of the Nor- 

 ^~^ wegian North Atlantic Expedition has just been 

 published, containing a memoir on the Actinida of the 

 North Atlantic, by D. C. Danielssen. It will be remem- 

 bered that this fine series of memoirs is published under 

 the sanction of the Norwegian Government, and with 

 some assistance from their Treasury. They have been 

 distributed to very many of the Academies and learned 

 Societies of the world, and reflect immense credit on the 

 zeal and intelligence of the Norwegian naturalists. 



All the specimens described by Dr. D. C. Danielssen 

 in this memoir were collected from deep water, and most 

 of them from the " cold area." These anemones, for the 

 greater part, proved capable of accommodating them- 

 selves to changes of habit and temperature, and it was 

 therefore possible to keep them alive for a considerable 

 period, during which their external characteristics were 

 observed and their portraits taken. That, despite the 

 heavy rolling sea so generally met with in the North 

 Atlantic, the artist has done his part well, is proved by a 

 glance at the first five plates which accompany this 

 memoir, which have been printed in colours by Werner 

 and Winter, of Frankfort-on-the-Main. 



This memoir represents the first serious attempt, since 

 the publication of Richard Hertwig's Report on the 

 Challenger Actinaria, to describe the sea anemones of an 

 extended area, taking their anatomical features as the 

 basis of their classification ; and it seems to us to justify 

 the remark that a very much larger series of facts must 

 be noted before an even fairly plausible scheme of classi- 

 fication of this group can be formulated. No doubt the 

 systems of Gosse and Andres, based for the most part on 

 mere external characteristics, have had their day ; but no 

 new scheme to take their place has yet been properly 

 developed ; a wider and closer anatomical investigation 

 of even well-known species must be undertaken ere this 

 can be looked for. 



