920 REPORT— 1893. 



Tliecal plates uumerous, indeBnite, with strong radial structure of stereom, but no 

 pore-rhombs. Brachioles branched ; columnals uniserial. Macrocystellidcs. 

 Thecal plates in three or four circlets, subject to somewhat regular pentamerism, 

 with radiately folded stereom, but no pores. Brachioles borne by upper circlet. 

 Tiaracrinid<r. Plates forming sides of theca are in not more than two circlets ; 

 with strong transverse pore-rhombs in each circlet. Malocystidee. Thecal plates 

 numerous, indefinite, radiately folded, no rhombs. Food-grooves on exothecal 

 processes pass over theca aud bear brachioles. Glyptocystidce. Theca of five 

 circlets of alternating plates, typically five in each circlet ; but in aboral circlet 

 r. post, and r. ant. plates are always fused. Anus between second and third 

 circlets in r. post, interradius. Hydropore in adoral circlet, opposite unpaired 

 food-groove, defines post. IR. Pectini-rhombs present, one always uniting 1. post. 

 plate of first aboral row with 1. ant. plate of second row. Food-grooves, bordered 

 by plates derived from proliferation of adoral circlet, pass over theca and bear 

 biserial brachioles. (Sub-famm. EchinoencrhnncB, CallocystincB, Qlyptocystinm.) 

 Caryocrinid(e. Thecal plates primitively in four circlets, dominated by trimerous 

 symmetry, and united by pore- rhombs. Food-grooves in adoral region are 

 hypothecal, then for a short space epithecal, and distally exothecal and brachio- 

 liferous. 



Order -j. Apokita. — Pentamerism affects food-grooves and thecal plates, 

 probably also nerves and ambulacral vet^sel.*, but not gonads. Food-grooves 

 eKOthecal and circumoral. No folds, pores, or rhombs. 



Fam. Crypt ocrinidee. Thecal plates in four circlets. 



Order 4. Diplopokita. — Radial symmetry affects food-grooves, and by dpgrees 

 the thecal plates connected therewith, but not interradial plates ; probably also nerves 

 and ambulacral vessels, but not gonads. Food-grooves epithecal (without interme- 

 diary of subambulacrals), also prolonged on exothecal brachioles, which line the epi- 

 thecal grooves. Stereom may be folded, but pore-rhombs not developed ; diplopores 

 always present in mesostereom, but restricted in distribution in higher forms. 



Fam. Sph<cronid(B. Food-grooves do not extend beyond adoral circlet. 

 Diplopores difi'use. GlyptospheeridcB. Food-grooves extend beyond adoral circlet, 

 and irregularly transgress sutures between thecal plates. Diplopores diffuse. 

 ProtocrinidcB. Food-grooves extend almost to aboral pole, and are regularly 

 bordered by alternating thecal plates (adambulacrals), which bear brachioles. 

 Diplopores diffuse or confined to adambulacrals, from which they are never absent. 

 Mesocystid^e, Food-grooves extend almost to aboral pole, bordered by alternating 

 brachioliferous adambulacrals raised above interambulacrals. Diplopores confined 

 to interambulacrals. Five interradial deltoids (A) surround peristome. Gompho- 

 cystidce. Food-grooves curve around theca ; no brachioles. 



Class II. BLASTOIDEA. — Five (by atrophy four) epithecal food-grooves, 

 lying on a lancet-plate (? always), pass between five A, and are bordered by alternat- 

 ing, brachioliferous adambulacrals. Peristome and all grooves have covering plates. 

 No extensions from gonads and ccelom alorg rays into brachioles; but, apparently, 

 nerves from aboral centre met in circumoral ring, whence branches passed beneath 

 food-groove and supplied brachioles. Basals (B) and radials (II) always defined; 

 sutures of thecal plates never cross the subvective areas. 



Grade 1. Peotoblasxoidea. — Thecal plates indefinite in number; no hydro- 

 spires. Fam. Asteroblttstidcc {Asteroblastus, Steganoblastus \ ?], Blastoidocrimts). 



Grade 2. Eublastoidba. — Thecal plates definite, in three circlets, viz., 3 BB, 

 5 RR, 5 A. Stereom of RR and A, on either side subvective areas, thrown into 

 folds rurming across radio-deltoid suture (hydrospires). 



Series Codovoblastida. — Fam. Codastirida (Eth. and Carp.). Hydrospire- 

 folds distinctly portions of the thecal plates, coming to the surface of the radial 

 sinus. No distinct hydrospire-canal or pores ; spiracles developed imperfectly or 

 not at all, {Cadaster, Phanoschisma, Cryptoschisma, Orophocrinus.) Pentre- 

 mitidcv. (Eth. and Carp, restr.). Ilydrospire-folds, usually numerous, concentrated 

 at the lowest part of the radial sinus, and partly or wholly pendent. Hydrospire- 

 canal opens through spiracles bounded distally by side-plates. Base convex. 

 Ambulacra rather broad. {Pentremitidea, Peiitreviites) 



