Revieivs — Fossil Echini, Panama. 85 



This is impossible to reconcile with the results of the examination of 

 peat-mosses and Arctic plant-beds in many parts of the British Isles, 

 and still more with the brilliant discoveries of recent years in 

 regard to the stages of palaeolithic culture and their relation to the 

 Pleistocene deposits. It is too early as yet to pronounce any decided 

 opinion on this subject, but, as Dr. Flett points out, there are signs 

 of a very decided reaction in this respect. If Professor Geikie went 

 too far in one direction, it is certain that his opponents went too far 

 in the other. The subject is a peculiarly difficult one, and it is 

 evident that long and patient investigation is still needed before 

 a final settlement can be reached. It will be conceded by all, what- 

 ever may be their personal predilections, tliat the life-work of James 

 Geikie played a leading part in the unravelling of this tangled skein, 

 and the authors of this book are to be congratulated on having given 

 a clear picture of a great man and a great geologist. 



li. H. R. 



II. — Fossil Echini- of the Panama Canal Zone and Costa IIica. 

 By KoBERT Tract Jackson. Proc. U.S. Nat. Mus,, vol. liii, 

 pp. 489-501, pis. Ixii-lxviii. 



THIS short and lavishly illustrated paper provides an account of 

 the Echinoids collected from the Oligocene-Miocene rocks 

 excavated during the making of the Panama Canal. The fauna thus 

 displayed is of a somewhat restricted, but characteristically American, 

 type. No Regular Echinoids are recorded, and the species described 

 belong to four genera only of Irregular forms. The two species of 

 Clypeasier (of which one, C. gatuni, is new) call for no special 

 comment. The three species of Encope {JE. annecfans, E. platytata, 

 and E. megatrema, all new) exhibit features of exceptional interest, 

 to which reference will be made below. The ^oYxioxj Eclmiolam'pas 

 is a well-known West Indian form. Of the three species of Schizaster, 

 two (/S. cristatus and S. panamensis) are new, but their preservation 

 is very imperfect. 



The genus Encope includes an extensive series of Scutelliform 

 Clypeastroids, characterized by marginal slits on the ambulacra, and 

 a solitary lunule perforating the posterior interambulacrum about 

 midway between the apex and the ambitus. This quality may be 

 considered as intermediate between that of Sciitella, in which there 

 is no lunule and hardly any development of marginal slits, and that 

 of Mellita, in which the interradial lunule is present, while the 

 marginal slits have become distally enclosed so as to produce 

 ambulacral lunules. The ontogeny of the latter genus shows that 

 the ambulacral lunules are developed from slits or notches around 

 which the test spreads in later gi-owth-stages, but that the interradial 

 lunule is formed by resorption of the test, and is thus a real 

 perforation. (There is one species of Mellita in which all the lunules 

 have the latter character, but this is quite exceptional.) 



In Encope anneclans, described in the paper under review, the 

 marginal (ambulacral) slits are in the stage of embayment normal for 

 species from the horizon (?Burdigalian), but there is no interradial 



