82 Revieivs — Oliver's Geology of St. Helena. 



With Ptilonaster the case is different, as this genus is stated to have 

 a quadruple series of ventral (ambulacral) arm-plates in place of the 

 double series in Protaster, etc. But after an examination of speci- 

 mens of P. Miltoni, I have some suspicion that the superficial (dorsal 

 and ventral) arm-plates, and the internal true ambulacral ossicles 

 have sometimes been confounded together. In the P. Miltoni before 

 me I can detect the scaled disc, the stellate mouth, the ophiura-like 

 arms, the lateral arm-plates with the spines, and the internal ossicles 

 (which are certainly neither bifid nor alternate, as stated in other 

 species), and I believe that these true internal ambulacral ossicles 

 have sometimes been described in Protaster, Tceniaster, etc., as 

 double dorsal or ventral arm-plates. The characters of P. Miltoni 

 are those of a true ophiuroid, and though the other species may be 

 in some respects enigmatical, I have no doubt that they are, after all, 

 true Ophiuroids. The " madreporite " is stated to lie on the back of 

 the disc in Protaster, a position that certainly would be very 

 aberrant. I can see nothing of this kind on the specimen before me, 

 and do not think the statement to be confirmed by the figures pub- 

 lished. In regard to Salter's Paloeocoma (not to be confounded with 

 D'Orbigny's genus), and the very analogous Devonian genus, 

 Aspidocoma, Goldf., I am incapable of deciding whether they are 

 Ojohiuridce or Asteriadce, though I have studied specimens of the 

 latter genus. 



I venture to publish these remarks in the hope that a critical 

 review of the fossil Ophiuridoe, from the pen of a Zoologist, who for 

 several years has made the recent ones the subject of his studies, 

 may be of some use, though the materials at my disposal are not 

 rich. In order that this part of Paleeontology may advance, more 

 attention must be paid to the recent forms than has hitherto been the 

 case. I will only add, that in an additional chapter I have dis- 

 cussed the intricate question whether Harlania Haiti (Arthrophycus, 

 Goppert), from the Silurian beds of North America, is really a Fucoid, 

 as supposed by most authors (compare the BTiysopliycus embolus of 

 Eichwald), and I have stated that I did not know anj'' natural objects 

 with which this fossil has a greater external likeness than the lower 

 arm-branches of Aster ojphy ton — leaving it to be decided, \>y those 

 having plonty of specimens at hand, if this presumed cryptogamous 

 plant should possibly turn out to belong to the animal kingdom, and 

 to the tribe Euryalce. C. F. L. 



las-viE^ws. 



I. — The Geology of St. Helena. By Capt. J. E. Oliver, R.A., 

 8vo., pp. 32, Jamestown, St. Helena, 1869. With a litho- 

 graphed Plate of Sections, printed at the Eoyal Artillery 

 Institution, Woolwich. 



WE have in this pamphlet the results of a geological examination 

 of St. Helena, by a Staff Officer lately residing there, who had 

 not seen Mr. Darwin's work on " Volcanic Islands," chapter iv. of 



