PALASTERINA FOLLMANNI. 235 



The first ad ambulacra! is the largest. The arm must have been uniformly 

 tapering, not petaloid. 



The interradii may extend to about the fourth or fifth adambulacral. There is 

 considerable variation in the different interradii. Some show no ossicles except 

 the odontophor. This latter plate has considerable resemblance in general form 

 to that in Eoactis, and suggests that Palasterina descended from a form with a 

 conspicuous odontophor. It differs from the odontophor in Eoactis in being more 

 swollen and in possessing a coarse pustulose ornament. 



Measurements.' — R: r :: 4 mm. (approx.) : 2 mm. 



Horizon ami Locality. — Wenlockian (Starfish Bed) ; (lutterford Burn, Pentland 

 Hills. 



3. Palasterina follmanni, Stiirtz. Plate XVI, figs. 3 — 7; Text-fig. 171. 



1890. Palasterina foil ma mi i. Stiirtz, Palseontographica, vol. xxxvi, p. 226. pi. xxix, figs-. 29 — 31a. 

 1900. Pseudopalasterina follmanni, Stiirtz, Verhandl. naturhist. Ver. preuss. Bheinl., vol. lvi, 

 pp. 219, 224. 



1914. Pseudopalasterina follmanni, Schuehert, Fossilium Catalogus, Aniiualia, pt. 3, p. 36. 



1915. Pseudopalasterina follmanni , Schuehert, Bull. 88, U.S. Nat. Mus., pp. 156, 157. 



Material. — There are nine specimens of this species in the British Museum (Nat. 

 Hist.), three figured by Stiirtz (nos. E. 3469, fig. 29; E. 3470, figs. 30, 30 a; 

 E. 3471, fig. 31), the remaining six registered as E. 5004 (specimen mentioned by 

 Stiirtz, p. 224), E. 13(325, E. 13G2G, E. 13G29, E. 13G35 and E. 13G3G. 



The photographs given on PI. XVI are designed to show the somewhat 

 varying appearances due to differences in fulness of growth. The smaller 

 specimens are compact in appearance, and post-mortem compression has not 

 greatly changed their outline. Age in the individual seems to have been accom- 

 panied by a considerable increase in the height of the arm. The general surface 

 of the body becomes, in consequence, more slightly built, and post-mortem com- 

 pression causes considerable distortion. The specimen photographed in PI. XVI, 

 fig. 4, has had its arms distorted by lateral compression, but the ossicles remain for 

 the greater part in their original apical position. That photographed in fig. 7 has 

 been subject to dorso- ventral compression, and the apical ossicles are forced into 

 some of the oral interradial areas. The series is valuable in supporting the view 

 that in other species of Palasterina, in which the material is not nearly so complete, 

 the large interradial areas are produced secondarily and were not a feature of the 

 living form. 



In several of the specimens the distal half of one or more arms is bent back, so 

 that, if only the oral surface be seen, the arms appear to be much foreshortened. 



This is noticeably the case in E. 13G29 (PI. XVI, fig. G), where all the arms 

 have been preserved in this way. 



Specific Characters. — See p. 220. 



