362 PROCEEDINGS OF THE ACADEMY OF [1888. 



Explanation of Plate XVIII. 



Fig. 1. Taxocrinus intermedius W. and 8p. 



ll Specimen sliowing the irregularly arranged interradial 

 plates and pouches along the free rays ; V!i posterior view 

 of the same sjDecimen, showing the lateral proboscis, and 

 the perisomic plates ; 1!: posterior side of another speci- 

 men, showing the proboscis and folds in the perisome ; 1^ 

 the proboscis and ventral perisome in another specimen ; 

 l!l ventral view of the same specimen as 11, showing the 

 ventral perisome, the ambulacra, mouth and parted orals. 



Fig. 2. Vault of Dorycrinus mississippiensis with an extremely 

 large posterior oral. 



Fig. 3. Vault of Agaricocrimis Wortheni. The orals very irregu- 

 lar and separated by small accessory pieces. 



Fig. 4. Vault of Platycrinus discoideus with more regularly ar- 

 ranged oral plates. 



Fig. 5. Vault of Batocrinus dypeatus, the orals pushed over to the 

 anterior side by the subcentral anal tube. 



Fig. 6!: Haploerinus mespiliformis, posterior aspect, showing the po- 

 sition of the anal opening ; 61 showing the 5 large anal 

 plates, and the tongue-like projection of the posterior 

 oral ; 61 another specimen, showing the "knopf" of Gold- 

 fuss at the upper end of the posterior oral, and the proxi- 

 mal arm joints. 



Fig. 7. Vault of a new species of Talarocrinus, with a single large 

 plate in the center. 



Fig. 8. Vault of Platycrinus Yandelli, the posterior oral pushed 

 out of place by the proboscis. 



Fig. 9. Vault of Platycrinus americanus with more regular orals. 



Fig. 10. Vault of Eretmocrinus coronatus. The orals very much 

 displaced by the proboscis. 



Fig. 11. Vault of Rhodocrinus Whitei, ap23arently without oral 

 plates. 



Fig. 12. Vault of a new Rhodocrinus from New JNIexico, like the 

 preceding species apparently without orals. 



