196 ECHINODERMATA PELMATOZOA SUB-KINGDOM in 



with very short limbs. Deltoids greatly enlarged and elongated, forming 

 over two-thirds of the entire calyx ; the posterior one wider than the others, 

 and divided by a large anal plate. Lancet-plate exceedingly long and narrow, 

 partly exposed. Side-plates numerous ; hydrospires two to each side of the 

 ambulacra. Summit covered by comparatively large orals, asymmetrically 

 arranged and forming a flattened disk which completely closes the peristome. 

 Devonian ; North America. 



Sub-Family B. SCHIZOBLASTIDAE. Etheridge and Carpenter. 



The posterior deltoid not divided by an anal plate. Posterior spiracles may be 

 fused with the anus. 



Schizoblastus, E. and C. Calyx resembling that of Granatocrinus in form. 

 Basals almost always confined to the lower face of the calyx ; deltoids of 

 variable size, but always visible in a side view. Hydrospires one to four tp 

 each ambulacrum. Spiracles small, slit-like, placed between the lancet-plates 

 and deltoid ridges ; the posterior pair sometimes confluent with the anus. 

 Sub-Carboniferous ; Ireland and North America. 



Cryptoblastus, E. and C. Calyx sub-globose, with a flattened or slightly 

 hollowed base. Basals and deltoids small. Lancet-plate separated from the 

 radials by a hydrospire-plate, which does not extend above the radio-deltoid 

 suture ; but above this line the lancet-plate meets the deltoids without leaving 

 any hydrospire-pores. Spiracles round, distinctly double at four of the sides, 

 but those of the posterior side confluent with each other and with the anus. 

 Summit covered by numerous, irregularly arranged small pieces. Sub- 

 Carboniferous ; North America. 



Acentrotremites, E. and C. Calyx elliptical, with broad pentagonal lower 

 face. Radials large, taking up three-fourths of the height of the calyx. 

 Deltoids unequally rhombic, each notched by two spiracles at the ends of the 

 radio -deltoid suture. Anal opening situated close to the summit in the 

 posterior deltoid. Ambulacral edges of the deltoids without hydrospire pores. 

 Sub-Carboniferous ; Great Britain. 



Family 4. Granatoblastidae. Etheridge and Carpenter. 



Calyx globular or ovoidal, with flattened or concave base, and long linear ambu- 

 lacra. Spiracles five, piercing the deltoids, or ten, grooving their lateral edges. 

 Sub-Carboniferous. 



Granatocrinus, Troost (Figs. 316, 318, A, B). Calyx ovate to globose. 

 Lower face from slightly concave to deeply funnel-shaped ; interradial areas 

 more or less depressed. Basals small, generally concealed in the central 

 columnar cavity. Radials very variable in size, often long, and invariably 

 turned in below to assist in forming the base. Deltoids also variable ; usually 

 unequally rhombic, but sometimes triangular; the anal deltoid frequently 

 differing from the others. Ambulacra nearly parallel-sided, always impressed 

 within the sinuses at their proximal ends. Lancet-plates narrow, not filling 

 the sinuses, and mere or less exposed throughout two-thirds of the ambulacra. 

 Side-plates transversely elongated*; outer side-plates generally well developed. 

 Hydrospires pendent, usually but two or three folds on each side of an am- 

 bulacrum ; the inner one forming a well-defined hydrospire-plate. Spiracles 



