Introduction to Animal Morphology. 1 29 



(Comarocystis) ; anus always present ; there were five lateral 

 ovaries (?) with openings, when present, surrounded by five 

 plates, almost always present ; the pillar is short, jointed, or 

 none. About 8 are known as fossils. Hyponome, from 



Cape York, Australia a small star-like free disc, ventrally 

 convex, with no calyx, and a dorsal scaly rosette is the 

 nearest living ally, and approaches Agelacrinus.* 



3. Crinoidea stalked, at least in early life, with a cup- 

 shaped body of calcareous plates, with from 2-18, but com- 

 monly five, solid, primary, often branching, arms, independent 

 of the visceral cavity, except at the base, and furrowed longi- 

 tudinally above for the tentacle-like pedicelli given off by the 

 ambulacral tubes lying in these medial grooves radiating from 

 the mouth. This system seems purely respiratory. The 

 arms can move rapidly, and can close over the oral disc for 

 protection ; they have laterally articulated pinnules appended. 

 Tin- ventral surface is, as in the last order, upturned ; the 

 dorsal stalked. 



The mouth is usually central, and in some fossil forms 

 mounted on a proboscis. The ciliated stomach winds around a 

 'iis spindle (compared to the lamina spiralis of 

 '. immalian cochlea). The anus may be ventral, between 

 two water-vascular furrows, or absent (?) (Holopus). The di- 

 canal never extends into the arms. The pseud- 

 haemal system consists of a central sacculus giving off 

 branches to the arms. The ovaries are external, membranous 

 lamel' ped under the soft skin on the ventral surface 



of the pinna;. The testes are similar, anil the products 

 emptied by dehiscence. 



The column rises from a root-like disc, adherent to some 



solid . i-ral are rooted together. The 



pillar itseli 1 calcareous joints, traversed 



Multiple axial canal. The joints arc united by 



mterarticular lamina. 1 of elastic vertical fibres, 



and Ifl bundles of unstriped musclo-iibrcs 



here and tin-re are whorls of jointed 



cirrhi. T: material of the calcareous plat' 



Ci .1: fin ins \\liu-h p< 



