424 



SCIENCE. 



[N. S. Vol. XI. No. 272. 



scutes on the carapace of the loggerhead turtle. 

 The material consisted in part of twenty speci- 

 mens of new-born loggerheads all taken from 

 one nest in New Britain and all showing ab- 

 normal numbers of scutes. This was supple- 

 mented by fifty-six other specimens from various 

 collections, making in all a total of seventy-six 

 individuals examined. The typical arrange- 

 ment of the scutes on the loggerhead is as fol- 

 lows : The chief axis of the carapace is covered 

 by six median elements ; these are flanked by 

 five pairs of costals ; and the edges of the cara- 

 pace are bounded by thirteen pairs of marginals. 

 In studying the variation of these parts, Gadow 

 has confined his attention to the median and 

 costal elements. The variations in these series 

 took the form of supernumerary scutes. Thus 

 the total number of median elements may rise 

 from six to seven or eight, and of costal ele- 

 ments on a given side from five, to six, seven, 

 or even eight. In the costal scutes the varia- 

 tions were in some instances symmetrical, in 

 others unsymmetrical. It will be observed that 

 all these variations lie above the normal, and, 

 as there is reason for believing that primitive 

 turtles had a greater number of scutes than 

 modern ones, Gadow holds that these varia- 

 tions are to be interpreted as atavistic. Ac- 

 cording to his belief, the ancestral turtles pos- 

 sessed at least eight median and eight pairs of 

 costal plates. The reduction of these by which 

 the condition in the loggerhead was reached, as 

 indicated by the variations observed, was as 

 follows : Of the original eight median scutes, 

 the seventh was probably the first to disappear, 

 followed by the fifth, thus giving rise to the 

 series of six, typical for the loggerhead ; of the 

 original eight pairs of costals, the second pair 

 was probably first lost, then the fifth and, by 

 the fusion of the seventh and eighth, the con- 

 dition of five pairs characteristic for this species 

 was reached. For variations of this atavistic 

 kind, Gadow, without further comment, pro- 

 poses the term orthogenetic, a rather summary 

 procedure in our opinion, since this term has 

 already been extensively ernployed by Eimer 

 for a different phenomenon. More or less 

 looseness, however, pervades the whole paper 

 and appears strikingly in the diagrammatic 

 figures VII. and VIII. (p. 217), which, though 



intended to make the subject clear, really lead 

 to confusion from the fact that the system of 

 cross-hatching adopted is incorrectly used. It 

 is to be regretted that a little more care was not 

 exercised in the preparation of what is other- 

 wise au interesting and valuable contribution. 

 The second paper in this part is by Dr. Willey 

 himself and deals with the South Pacific and 

 West Indian Enteropneusta. To the five species 

 of these worm-like animals previously known 

 from the region in which Dr. Willey collected, 

 three new species are added. Two other new 

 species from the West Indies are also described. 

 The paper contains a synopsis of the families 

 and genera of the Enteropneusta and a full de- 

 scription of the new species. These organisms 

 are of importance because of their supposed re- 

 lation to vertebrates, and the concluding part 

 of Willey's paper deals with their morphology 

 from this standpoint. A comparison of the 

 central nervous organs, of the supporting axis 

 of the body, of tubules kidney-like in character, 

 and of the gills in the Enteropneusta, the tuni- 

 cates, and the vertebrates confirm the belief in 

 the natural aflinities of these three groups of 

 animals. In the course of this discussion the 

 author suggests the novel idea that the genital 

 glands and gill-slits were primarily unlimited in 

 number and coextensive in distribution, and that 

 the primary function of the gill-slits was the 

 oxygenation of the genital glands, their second- 

 ary function being the respiration of the indi- 

 vidual. 



The concluding paper is by Shipley and deals 

 with the five species of Echinoids collected by 

 Willey. A revision of this group of worms is 

 given together with an account of their geo- 

 graphical distribution. 



G. H. Parker. 



Minnesota Plant Life. By Conway BIacMillan. 



Report of the Survey ; Botanical Series, III. 



St. Paul, Minnesota, October 30, 1899. 



Octavo, 568 pages. 



This is probably the most remarkable State 

 report ever published. The author has given 

 to the world a thoroughly scientific treatise, 

 which is a contribution to our knowledge of the 

 flora of Minnesota, and yet he has done so in 

 such a way that, at the same time, the volume 



