426 DR F. A. BATHER. 



§ 260. To express these conclusions in taxonomic form : while one might associate 

 Trochocystis, Ceratocystis, and Coihurnocystis in some larger subdivision of the 

 Heterostelea, it would not be proper to place Cothu^mocystis with one of them more 

 than with the other. Either the Family Anomalocystidae must be retained for these 

 genera as well as all those previously included in it (Bather, 1900, p. 49); or, if 

 Jaekel's Families Trochooystidae and Ceratocystidae be accepted, then a new Family 

 Cothurnocystidae must be placed by their side. It is the latter course which, in 

 the absence of known connecting links, I have thought it more prudent, to adopt 

 on this occasion. 



Order: RHOMBIFERA. 



§ 261. Diagnosis. — Cystidea in which radial symmetry affects the food-grooves and, 

 in the more advanced families, the thecal plates ; probably also the nerves and 

 ambulacral vessels, but not the gonads. Food-groves supported on exothecal skeletal 

 processes (brachioles), which are either close to the mouth, or are removed from it 

 upon a series of special plates lying outside the thecal plates, or are separated from 

 the oral centre by hypothecal passages passing beneath tegminal plates. Stereom and 

 stroma in folds (rhomb-ridges) at right angles to the sutures of the thecal plates, which 

 folds are specialised as pectinirhombs in higher forms. 



This diagnosis is the same as that previously given by me (Dec. 1906, p. 13). 



§ 262. The Families previously included by me in the Rhombifera (Feb. 1899 and 

 1900) are: Echinosphaeridae, Comarocystidae, Macrocystellidae, Tiaracrinidae, Malo- 

 cystidae, Glyptocystidae, Caryocrinidae. 



Prof. Jaekel (May 1901) has removed the Comarocystidae and Malocystidae 

 to his Class Carpoidea. Since that is a systematic conception which I am unable to 

 accept (§ 16), I leave those Families in the Rhombifera. 



§ 263. Of the genera included in my Family Macrocystellidae, Dr Jaekel (1899) 

 does not mention Lichenoides Barr., but agrees with me in regarding Mimocystis Barr. 

 as not essentially different from Macrocystella. The latter genus finds no place in his 

 system of the Cystidea, but is held to be a link between primitive Cladocrinoidea 

 (Jaekel) and the Chirocrinidae (Jaekel). Since Macrocystella is not a Crinoid, accord- 

 ing to my definition of that Class, but a Cystid, I leave it in the Rhombifera. On the 

 present occasion its relations to the Chirocrinidae (Jaekel) are all that need discussion. 

 While Dr Jaekel takes it for a direct ancestor of Chirocrinus, I have regarded it rather 

 as showing "an early development of that tendency to reduce the number of plates, 

 which eventually evolved the Glyptocystidae from a different branch of the Rhombi- 

 fera " (1900, p. 56). 



§ 264. There remain of my Families, the Echinosphaeridae, Tiaracrinidae, Glypto- 

 cystidae, and Caryocrinidae. These are placed by Dr Jaekel in an Order Dichoporita, 

 diagnosed by the presence of pore-rhombs and of special skeletal elements supporting 

 the subvective grooves on the theca. They are divided into two Suborders : RegularJa 



