86 
Triassic Echinoderms of Bakuny. 
It runs as follows: «Palaeozoic Cidaridae of small size, with sharply bevelled 
adambulacral margin of the interambulacral area. Few coronal plates. Main tubercles 
small, crenelate. Scrobicules elliptic, rather sunk, confluent; scrobicular ring not 
marked » Comparison of this with Doederlein’s diagnosis of Miocidaris shows that 
the only distinctive feature in the latter is scrobicules «round». None the less 
Lambert separated the two genera, considering Miocidaris , with its circular scrobi¬ 
cules, as a descendant of Eotiaris with elliptic scrobicules. The objection to such 
a reversal of the usual order of evolution has already been explained, and doubts 
have been cast on the value of the character as a generic criterion. Apart from 
this, the character is not always so marked as is generally asserted. The scrobi¬ 
cules, it is true, are elliptical, but they are not always confluent, for specimens in 
the British Museum (E1119, E1121), from the Bryozoan dolomite of Pössneck, show 
a line of granules separating the larger scrobicules. Search for a more reliable 
diagnostic discovered the assertion of a difference in the adradial suture, which 
Doederlein described as smooth in Eocidaris Keyserlingi. It has, however, 
been shown above that it may be denticulate both in that species and in C. 
grandaeva. 
Consequently there appears to be no essential difference between Miocidaris 
and Eotiaris. 
It is perhaps advisable to explain that the genus Eocidaris is in no way 
affected by this conclusion. Following A. Tornouist (1896 and 1897) and J. Lambert 
(1900), I find that Eocidaris Desor has become restricted to E. laevispina and 
E scrobiculata alone among the species originally referred to the genus, and I 
therefore fix on the former of these as genotype, taking as lectotype of the species 
Sandberger’s pl. XXXV, f. 2a (1855). (See further Bather, 1908). 
It may also be pointed out here that the species Archaeocidaris Verneuilana 
King, which Lambert has referred to his genus Permocidaris (1900), is closely 
allied to, if not identical with Miocidaris Keyserlingi, as indeed many authors 
have believed. This, however, does not bring Permocidaris into the synonymy of 
Miocidaris, for it is based on Cidaris Forbesiana Köninck, which appears from 
Waagen’s description (1885, p. 819) to be quite a distinct genus. 
Structure of Miocidaris. — Doederlein’s diagnosis contained the Statement 
«pores notyoked» whereas Cidaris subcoronata was said by him to have «pores yoked 
(? !)». Notwithstanding the inclusion of that species in Miocidaris , I have retained the 
«pores notyoked», partly because thecontrary assertion was from the beginning exceed- 
ingly doubtful, partly because in an ambulacral fragment from the Pachycardien- 
tuffe of the Seiser Alp, found in association with interambulacrals referred by Broili 
(1904) to Cidaris subcoronata, the pores are not yoked. The Statement is, however, 
liable to correction, for the ambulacra are not yet known in the genotype, M. Cas- 
siani, or in M. Keyserlingi (including Verneuilana), or in various other species. 
Little attention has hitherto been paid to the sutures between the inter¬ 
ambulacral plates themselves in these Streptosomatous Cidaridae. They are, however, 
of much interest, for, in Miocidaris at any rate, they frequently show signs of a 
flexible, and to some extent an imbricating, union. (Compare text-fig. 7, p. 60). 
Spandel (1898, p. 34) has stated that in M. Keyserlingi the adoral margin of each 
interambulacral has a convex curve, and is «nach innen abgeschrägt», while the adapical 
margin has a concave curve and is «nach aussen abgeschrägt», but with a ridge 
