364 DR F. A. BATHER. 



B. SYSTEMATIC DESCRIPTION. 



Order: AMPHORIDEA. 



§ 13. Diagnosis. — Primitive Cystidea in which radial symmetry has affected neither 

 food-grooves, nor thecal plates, nor (probably) nerves, nor ambulacral vessels, nor gonads. 



§ 14. This diagnosis is the same as that previously given by me (Feb. 1899 ; Mar. 

 1900; Dec. 1906) and the reader is referred to the remarks that previously accom- 

 panied it, especially on the last occasion. It is a negative definition ; indeed, it can 

 hardly be said that any true diagnostic character justifies the union of the various forms 

 referred to the Order. A genus here and there may, as our understanding of it deepens, 

 be fittingly removed to one of the more rigidly established Orders ; or additions to the 

 number of known genera may render it practically convenient to break up the Amphor- 

 idea into other Orders, each with a more positive diagnosis. This provisional character 

 of the Order has always been admitted, indeed insisted on, by me, and especially have 

 I pointed to the Anomalocystidae as constituting a group that would demand independ- 

 ence as an Order, Anomalocystida. Two reasons now force me to discuss this demand. 

 First, the discovery by Mrs Gray of a singular Pelmatozoon which raises many difficult 

 questions in this connection. Secondly, the fact that Prof. Jaekel's attempt to found 

 a new Class, Carpoidea (May 1901), seems to be gaining some acceptance. Let us 

 deal with his proposals first. 



§ 15. Dr Jaekel divides the Pelmatozoa into 6 Classes : (1) Cladocrinoidea, and (2) 

 Pentacrinoidea, which together equal the Crinoidea of most authors ; (3) Cystoidea, (4) 

 Blastoidea, and (5) Carpoidea, which three he groups as aberrant types ; (6) Thecoidea, 

 which equals the Class Edrioasteroidea. 



§ 16. The Carpoidea comprise the genera that I have grouped under the Families 

 Dendrocystidae, Anomalocystidae, Malocystidae, and Comarocystidae. Dr Jaekel 

 splits these Families up, and founds also the Family Ceratocystidae, for a new genus 

 allied to the Anomalocystidae, and the Rhipidocystidae, for a new genus near 

 Dendrocystis. The following is his definition of the Class : — " Carpoidea are aberrant, 

 irregular Pelmatozoa, whose ambulacral organs are only in loose relation to the thecal 

 .skeleton and have, as a rule, produced only slight traces thereon. Theca a closed 

 capsule, with mouth and anus in its wall, never pentamerous, often distorted, usually 

 compressed dorsal-ventrally, more or less symmetrica] right and left. Ambulacra 

 developed in two radii. The elements that bear the ambulacral grooves (so far as known) 

 are uniserial. Base tetramerous or trimerous. Stem usually composed of symmetrically 

 biserial coluranals, and in part provided with genital appendages metamerically arranged. 

 Restricted to Cambrian and Silurian [sensu latissimo]." 



§ 17. It will at once be evident that the essential and universal statements in this 

 definition correspond with my definition of the Amphoridea. There is also a positive 



