16 DESCRIPTION OF 



PLATE XV. 



Fig. 1. PENTREMITES WORTHENI. 606 



1. View of a specimen, showing on the left side parts of two pseudambu- 



lacral areas. [The number of pieces in the pseudambulacral areas 

 is about twice as many as represented in the figure.] 



Fig. 2. PENTREMITES BIPYRAMIDALIS. 607 



2. View of the antero-lateral side. [The summit and base of the figure are 



too wide, and the number of poral pieces represented is little more 

 than one-half the true number.] 



Fig. 3. ACTINOCRINUS PERNODOSUS. 608 



3 a. Base of the specimen, the posterior side being uppermost. The right 

 postero-lateral ray has the arm-bases broken off close to the body, 

 which gives a somewhat unequal appearance to the two sides. 



3 b. Anterior view of same, showing the summit of the third radial plate. 



Fig. 4. ACTINOCRINUS NASHVILLE. 609 



4. View of the postero-lateral side of a large specimen. 



Fig. 5. ACTINOCRINUS LOWEI. 611 



.6.0. Anal side of specimen. 



5 b. View of right antero-lateral side, the arm -base of which is smaller 



than the otheis. The cavity near the summit is only from the breaking 

 away of some of the plates, and is not an organic feature. 



. 

 Fig. 6. ACTINOCRINUS GOULDI. 613 



G a. The anterior side of specimen, showing the base of arms and anterior 

 spine, with portions of two others on the left side. The left antero- 

 lateral spine is essentially entire, the representation being to make 

 room for the separate spine on that side. The postero-lateral spine is, 

 by error, represented as smooth in some of the figures. 



6 6. The central spine of a larger individual, showing the slightly curved 



form and spiniferous character above, while it is nearly smooth toward* 

 the base : the latter feature is not always characteristic. 



Fig. 7. ACTINOCRINUS RAMULOSUS. 615 



7. View of a distorted specimen, showing the base and three of the rays. 



