g Echinodermata. 



plate consists of a double row of anchylosed covering plates. A comparative 

 study of the characters of the basals and top stem-joint in the apparently mono- 

 cyclic Neocrinoids leads to the conclusion either that they do not conform to the 

 rules of basal structure which hold good for all Palaeocrinoids , or that under- 

 basals were present in the larva and have since become concealed. 



Carpenter ( 2 , 3 ) criticises the views of Wachsmuth & Springer that the proximal 

 dome-plates of Palaeocrinoids represent the interradials of the abactinal side, 

 and defends his statement that the 5 plates covering the peristome of Allagecrinus 

 and Haplocnnus are orals and not calyx - interradials [see Bericht for 1885 I 

 p 188]. Arguments are brought forward against the transfer of Encrinus to the 

 Palaeocrinoids ; and various genera of Neocrinoids are mentioned which do not 

 conform to the rules of basal structure that hold good for the Palaeocrinoids. 

 W. & S.'s description of a pliant ventral covering of interradial plates above the 

 arm-bases of Crotalocrinus is due to misinterpretation of Angelin's figures ; and 

 the conclusions drawn from it, respecting the summit structure of Reteocrinus and 

 other genera, are therefore unsound. 



V. Koenen (') describes the structure of the vault in several Devonian Cri- 

 noids, and points out its value as a specific character, v. Koenen ( 2 ) describes 

 the vault of Corylocrinus (n. g.) as formed of 4 plates meeting in the centre. One 

 is pierced by numerous pores , another by the anus (?) , while each of the others 

 has an impression which perhaps denotes the attachment of an arm. In Juglan- 

 docrinus (n. g.) there is a central summit plate surrounded by 6 others, beyond 

 which are 3 larger plates , 2 equal and 1 smaller. At the junction of each of 

 these with the corresponding proximal is a pair of minute openings of uncertain 

 nature. 



Gottsche points out that the composition of the calyx in Hemicosmites , Caryo- 

 crinus , Caryocystites and others of the simpler Cystids shows a considerable ano- 

 logy with that of certain Palaeocrinoids. 



Many of the observations described in the comprehensive work of Etheridge & 

 Carpenter on the Blastoids have been already noticed [see Bericht for 1882 I 

 p 181 ; and 1883 I p 142]. They are here grouped under the following heads. 

 1. The Stem and Calyx. 2. The Ambulacra. 3. The Summit -plates. 4. The 

 Hydrospires and Spiracles. In accordance with the views of Wachsmuth & Springer 

 the deltoids are now regarded as interradial plates, and not as homologous with 

 the orals of Neocrinoids. Those of Troostocrinus are unsymmetrical, the anal one 

 appearing externally, but the others not. Various monstrosities are mentioned, 

 among them 4- and 6- rayed individuals. The water-vessels were probably 

 contained within the canals of the lancet -pieces which are connected with an 

 oral ring, that of Grwatocrinus Nonvoodi being double. The structure and ex- 

 ternal communications of the hydrospires are described in detail. There may be 

 from 1 to 8 lamellar tubes in each hydrospire sac, which probably served both for 

 respiration and for discharge of the genital products as suggested by Ludwig. 

 Water entered by the marginal pores of the ambulacra and passed out by the 

 spiracles, when present. The hydrospires are limited to the radial and interradial 

 plates and have their slits parallel to the ambulacra. These characters, together 

 with the constancy in the number of calyx-plates and the perforation of the lan- 

 cet-plate, sharply distinguish the Blastoids from the Cystids. The basals are 

 symmetrical in all the genera but Astrocrlnus and Eleutherocrinus ; while in these 

 two, together with Pcntephyllum, one radial (probably the right posterior) and the 

 corresponding ambulacrum are strikingly different from their fellows. These 

 3 genera thus constitute the order Irregulares. 



