A MONOGRAPH OF THE EXISTING CRINOIDS 289 



a more or less similar development of spines being characteristic of many forms in the 

 allied family Thalassometridae. 



The four varietal types in Crinometra brevipinna may be arranged hi the order 

 of their presumed development as follows: 



Pulchra type 



Granulosa type 



Spinosa type Insculpta type 



The Insculpta type is much the commonest, and is the only type known to occur 

 at St. Helena. In the Caribbean area all the types appear to be generally distributed, 

 and on the basis of the meager data at present available there is no demonstrable differ- 

 ence in their bathymetrical and thermal relationships. 



In the discussion of the several varieties the brief synonymy given is merely a key 

 to the references given in the full synonymy under the specific name. 



Under the varieties only the localities from which each is definitely known are 

 given. The full data for these localities may be found by consulting the list of the 

 localities at the end of the account of the species. This full list of localities includes 

 many of the specimens that have not been allocated according to variety because 

 they are too young to have developed the characteristic varietal features, or for other 

 reasons. 



KEY TO THE NAMED VARIETIES OF CRINOMETRA BREVIPINNA 



a 1 . Division series and arm bases with more or less developed tubercular, granular, or spinous ornamen- 

 tation, at least along the borders of the ossicles. 

 b 1 . Ornamentation consisting of blunt tubercles, humps, knobs, rounded ridges, or granules, never 

 of spines. 

 c 1 . In addition to the chief ornamentation there are small tubercular, dentate, or spiny ex- 

 crescences, usually coalesced into lamellae, on the lateral borders of the division series and 

 first three brachials. 

 d l . The fine lateral excrescences are highly developed; the lateral borders of the ossicles as 

 far as the third brachial are strongly everted; median ornamentation of the ossicles of 



the divibion series mostly knoblike insculpta (p. 291) 



d 2 . The lateral excrescences are qualitatively and quantitatively less developed; the lateral 

 borders of the elements of the division series and first three brachials are only slightly 

 everted; median ornamentation of the ossicles of the division series more humplike. 



gracilis (p. 296) 

 c'. No small excrescences on the lateral borders of the division series and lowest brachials. 

 d l . Lower brachials, beyond the arm bases, with thickened and usually produced and everted 

 distal ends. 

 e 1 . Lower brachials beyond the basal with greatly produced distal edges which are turned 

 proximally over the dorsal surface in the form of a lip. 

 />. Proximally recurved liplike distal ends occur on the &-10 brachials following the tenth; 

 from the third, eighth, or tenth brachial strongly thickened distal ends are developed 

 from the middle of which a smooth, often quadrangular, swelling or broad tubercle 

 extends proximally downward over the dorsal surface. 

 g l . Entire surface of the elements of the division series thickly beset with equal sized 

 and uniformly distributed usually blunt tubercles of moderate size, which may be 

 coalesced; only exceptionally a larger shield-shaped median ornament. 



pulchella (p. 297) 



843803—50 20 



