1568 APPENDIX. 



developed arms. Sessile or stalked. Echinosphcerites, Dendro'- 

 cys fifes, Caryocystites, Arachnocystites. 



" III. Order Pleurocystid^e. — Test shortly stalked and asym- 

 metrical, the plates of the two sides being differently arranged 

 except in the oldest genera (Trochocystites). Arms few and small. 

 Pleurocystites, Ateleocystites, Balanocystites, Mitrocystites. 



" The above scheme takes no account of such types as Caryocri- 

 nus, Porocrinus, Echinoencrinus, Zepadocrinus, Ca/locystites, and sev- 

 eral other forms in which the plates of the test are few in number, 

 with a more or less regular arrangement as in the Crinoids ; while in 

 Cystoblastus and Asteroblastus there is a calyx very similar to that 

 of the Blastoidea. Most of these genera have hydrospires, either 

 generally distributed on the calyx plates (Caryocrinus), or limited 

 to a few of them as in Echinoencrinus, while Asteroblastus has 

 diplopores. 



"As at present constituted the class of the Cystidea is an extremely 

 heterogeneous one, and much further investigation will be necessary 

 before anything like a natural classification of the group becomes 

 at all possible." 



Bactrites (p. 846). 



According to the observations of Branco (' Zeitschr. d. Deutschen 

 Geol. Gesellschaft,' Bd. XXXVII., 1885), the initial chamber of 

 the shell of Bactrites is an ovoid and dilated sac, similar to that of 

 the shell of the Ammonoids and of Spirula. The genus Bactrites 

 must therefore be removed to the Ammonoidea. According to the 

 views of Branco, the genus should be ranked with the Goniatitidce, 

 the particular group of these to which it is referable occupying an 

 intermediate position, as regards the form of the initial chamber, 

 between the Ammonitidce and the Belemnitidce. 



II VERTEBRATA. 



Pisces. 



Chimeroidei. — As is mentioned in the Addenda, Mr Smith 

 Woodward has recently made the genus Myriacanthus (p. 951) the 

 type of the family Myriacanthidce, which is defined as follows : 

 Body elongated ; anterior dorsal fin placed above the pectoral, and 

 furnished with a long, straight spine. Teeth forming two or three 

 pairs of thin dental plates in the upper jaw, the hinder pair alter- 

 nated and not closely approximated in the middle line ; lower teeth 

 consisting of a pair of large dental plates meeting at the symphysis, 

 and a median incisor-like tooth in front. A few dermal plates on 

 the head ; and a long prehensile spine upon the muzzle of the male. 



