32 Reviews — Wachsmuth 8f Springer's Monograph on Crinoids. 

 I^ E "V" I IE AAT S. 



I. — Wachsmuth and Springer's Monograph on Crinoids.^ 



Fifth Notice. 



^^rpHE Anal plates," say Messrs. Wachsmuth and Springer, on 

 X. p- 124, " bear a most important part in the phylogeny of 

 PalEeozoic Crinoids, and are also of high importance in respect to 

 classification." This admission necessitates careful inquiry into the 

 homologies of those plates. The views of our authors " have under- 

 gone considerable modification"; but the discussion need not be 

 complicated by allusion to earlier publications, however great their 

 quondam value, except when they have been cited as evidence in the 

 present Monograph. 



The term 'anal plates' (analia) is now restricted by Wachsmuth 

 and Springer to such plates of the posterior interradius as (1) "are 

 directly or indirectly connected with the anus," (2) " take part in 

 the dorsal cup ; the others being plates of the anal tube " (tube- 

 plates). The first restriction forbids the application of the term to 

 such of the posterior interradials as are serially homologous with 

 those in other interradii of the individual ; it is practicable and 

 natural. The second restriction merely evades one difficulty and 

 creates another. For instance, in such a Camerate genus as Glypto- 

 crinus (Fig. 1), the plates of the cup proper merge so gradually into 

 those of the tube proper that no two observers would agree upon 

 the line to be drawn between them in any one specimen ; further, 

 owing to the gradual growth of interbrachials, plates that are free 

 tube-plates in the young become fixed cup-plates in the adult, just 

 as fi-ee brachials become fixed. Again, in such Inadunate genera as 

 Delocriniis^ (Fig. 9) and Ulocrinus (Fig. 3), it is hard to see, from 



il 



a-^Q^ 



Fig. 1. — Glyptoci'iniis decadactylus. 

 I. From posterior interradius (after "W. 

 and Sp.), showing ar, the anal ridge, 

 dividing the interbrachials, iEr. 

 II. Another interradius, for com- 

 parison (after Meek) . 



Fig; 2. — Anal area of ' Ulocrinus ' 

 Blairi (based on Miller & Gmiey's 

 figure). This is not Ulocrinus, 

 but represents a stage between 

 Eupachycrinus and Ulocrimis. It 

 strongly supports the homology 

 here adopted for the anals of 

 Ulocrinics. 



1 The North American Crinoidea Camerata. By C. Wachsmuth and F. Springer. 

 Mem. Mus. Comp. Zool. Harvard, vols, xx and xxi, containing 838 pp. and 8a plates. 

 (Cambridge, U.S.A., May, 1897.) For First, Second, Third, and Fourth Notices, 

 see GEOLfMAG. for June, July, September, and November, 1898. 



2 Miller and Gurley, 1890 = Cmocri'«?<s White pars, 1880, non Desor, 1845, nee 

 Koniff in tabb. iueditis. 



