102 Mr. W. Percy Sladen on the 



ture to whicli I wish to draw attention is the presence of a 

 remarkable glandular organ upon the stem or pedicel of the 

 jped. globiferce of 8. granulans, situated between the middle 

 portion of the shaft and the distal extremity to which the 

 valvate head is attached. Normally the presence of this 

 organ is superficially manifest as a conspicuous dilatation 

 upon the shaft. When examined with a lens of low power 

 the dilatation is found to possess a tripartite form, apparently 

 in correspondence with the divisions of the head of the pedi- 

 cellaria ; and near the upper portion of each of the three sec- 

 tions or separate sacculi there is to be seen a small foramen 

 or pore, through which a glairy mucous matter is extruded as 

 occasion requires. 



The discharge of mucus, it should here be mentioned, is 

 not solely confined to these organs upon the stem ; for a similar 

 secretion is also copiously ejected from the saccular head of 

 the pedicellaria globifera, under certain conditions which 

 will hereafter be referred to. 



These circumstances led the author, whilst studying at the 

 Zoological Station at Naples, to pay some attention to the 

 subject ; and it is upon the notes and preparations there made 

 that the present communication is in a large measure based. 



When a specimen of 8. granulans is placed in fresh water, 

 the animal frequently throws off a considerable quantity of 

 slime or mucus, as if in an endeavour to free itself from the 

 obnoxious environment. This exudation is found to proceed 

 from the pedicella?'ice globifercej and, so far as I have been 

 able to observe, I am disposed to think that its origin is refer- 

 able entirely to these appendages. It may be remarked in 

 passing, however, that this procedure is not confined to the 

 species under notice, nor yet to the group of the "regular" 

 Echinoidea ; for Echinocardium and some species of starfish 

 may be seen to behave in a similar manner when subjected to 

 the same treatment ; indeed the discharge from the Spatan- 

 goid is much more copious than in the case of 8. granulans. 



The pedicellarim globiferm of 8. granulans are readily 

 distinguishable from the accompanying ped. triphglloi and 

 ped. tridenteSj which are found upon the same test. Apart 

 from their larger size, the head has the appearance of being 

 fleshy and globose; and the jaw-pieces or valves are enveloped 

 in large membranous sacs j whilst the distal extremity of the 

 internal calcareous skeleton-frame is sharply bent at a right 

 angle from the main axis of the jaw-piece, and attenuated 

 into a long, sharp, tooth-like process or fang that protrudes 

 from the saccular development | just mentioned, and which, 

 when the pedicellaria is closed, meets in the centre with the 



