ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 255 



pores on the surface of the genital and pseudocular plates. The 

 rule that in secondary and living Echinids the water-pores are limited 

 to a single plate (madreporite) has some remarkable exceptions; 

 Cotteau has already described in Micropedina coiteaui the presence 

 of three perforated genital plates ; and, likewise, Discoidea infera has 

 pores on all the five genitals. There is an analogous arrangement in 

 Echinococcus, one, two, three, or four genital plates being perforated ; 

 in Hemtpneustes the pores are small, and are found not only on two 

 or four genital, but also on the three anterior ocular plates. The 

 author concludes that when the pores are found on one plate only 

 this is not because they are there concentrated, but because they have 

 disappeared from the other plates. 



The arrangement of the genital apertures is next discussed, and 

 genera with only three [Isaster, Pericosmus, &c.) or two [Ditremaster) 

 are cited ; when one genital pore disappears it is the madreporite 

 that is affected, and next that which is found opposite to it, or on the 

 left side. 



Deformities of Fossil Crinoids.* — Prof. L. von Graff gives an 

 account of the various deformities produced in recent Crinoids by 

 the presence of parasitic Myzostomida, and enumerates the instances 

 of deformities in fossil forms which seem to indicate that they also 

 suffered from these parasites. He concludes that the Myzostomida 

 existed in the carboniferous period, and are, like their hosts, among 

 the oldest of known animal organisms. 



Revision of the Palaeocrinoidea.t — In the third part of their 

 revision Messrs, C. Wachsmuth and F. Springer discuss the classi- 

 fication and relations of the brachiate Crinoids, and conclude the 

 generic distinctions. The authors find that the interradials are repre- 

 sented in all groups of the Palseocrinoids, were early developed in 

 the larva, attained at once large proportions, and were later on either 

 persistent or absorbed ; they extend as far as, or even cover over the 

 proximals, and they are more extravagantly (not in number but in 

 size) developed in the earlier groups. The orals appear to be repre- 

 sented only by the central plate. 



The authors discuss the differences between the Palfeocrinoids 

 and Neocrinoids, and while agreeing generally with Dr. P. H. 

 Carpenter (whom they seem to have somewhat misunderstood), they 

 think that too much stress has been laid upon the asymmetry of the 

 calyx, and that not sufficient value has been attached to the presence 

 of interradials in the former. They propose their own diagnoses of 

 the two groups. They regard the Pelmatozoa as a class of the 

 Echinodermata, of which the Anthodiata and the Crinoidea are the 

 two subclasses, and these they, likewise, diagnose. The Palaeo- 

 crinoidea are divided into the suborders Camerata, Articulata, and 

 Inadnnata. 



* ' Palseontographica,' xxxi. pp. 185-91 (1 pi.). 



t Troc. Acad. Nat. Sci. Philad., 1885, pp. 225-364 (6 pis.). See also Dr. P. 

 H. Carpenter in Ann. and Mag. Nat. Hist., xvii. (188G) pp. 277-89. 



