ROEMER ON THE PENTREMITES. 



9 



ner lamiiine in two rows alternating with each other, and at length 

 towards the extremity larger laminar pieces in a single row. In the 

 specimen described the last are placed vertical to the plane of the 

 tentacular space {Fiihlerfeld), whilst the other part of the appendage 

 lies with its broad side on the plane of the space. 



The length of the pinnulse is very considerable in relation to their 

 thickness : some of those originating at the lower extremity of the 

 jBeld can be followed even beyond the point of the interscapulary tra- 

 pezoidal piece. 



The direction of all these appendages is very accurately towards 

 the vertex of the shell ; consequently in the middle of the tentacular 

 space they lie thickly compressed on each other, and this seems to 

 have caused that half-turning round of the tentacles, so that the 

 laminar portion of the upper extremity comes to be vertical to the 

 shell. 



The number of the pinnulse in each row of a space (Feld) is about 

 fifty, which is also about the number of the holes in a row of the un- 

 covered, so-called, ambulacral space of a Pentremite of nearly the 

 same size. 



In the annexed drawings, which my friend Dr. Ewald has had the 

 kindness to prepare, all the circumstances described are represented 

 with remarkable fidelity and care, and render any further description 

 unnecessary. 



Fig. b. 



Fig. c. 



4P 

 / ■ . 



Fig. a. is a view of the specimen of the natural size. 

 Fig. b. a view of a tentacular space with the pinnulee, magnified 

 two times. 



Fig. c. a single pinnula, magnified three times. 



The most general result regarding the structure of the Pentremite 

 that may be deduced from the consideration of this specimen is : — 

 "The minute pores which penetrate the ambulacral spaces of 



