NORTH AMERICAN STARFISIIIvS. 105 



Linckia Guildingii. 



Linckia Guildingii Guay, 1810. Ann. Mag., W. 



PI XIV. FlfjH. 1-0, 



A longitudinal section of one of the arms (PI. XIV. Fig. 6) shows the. 

 great thickness of the irregularly shaped polygonal plates composing tlie 

 limestone network of the abactinal surface. The plates (as seen in Fif/. 4, 

 PI. XIV., when they are denuded of the finer granulation covering them, 

 PL XIV. Fig. 1, and the intervening spaces) are very closely packed ; the 

 processes connecting plates laterally often do not exist in the median space 

 of the arrn, and appear only as short rods along the sides of the arms and 

 on the outer edge of the lower surface (PI. XIV. Fig. 3), where they are 

 closely packed, forming in older specimens a compact pavement, and 

 losing on this surface the imbricating arrangement to be traced only 

 along the sides of the arms or to be seen in a transverse section. The 

 fine granulation mentioned above extends over the whole actinal surface 

 of the arms, concealing almost completely the three to four longitudinal 

 rows of small plates immediately succeeding the interambulacral plates 

 (compare Figs. 2 and 3, PI. XIV.; see also Fig. 2'). 



The top of the large papillae (PI. XIV. Fig. 6) attached to the interambu- 

 lacral plates forms a close pavement when seen from the actinal side ; 

 these large papillce pass very rapidly into the minute granules covering the 

 lower side of the arms (PI. XIV. Fig. 2). Toward the actinostome the pa- 

 pillae flare inwardly, forming several rows placed one behind the other, and 

 appear, when seen in section, as if there were a series of secondary inter- 

 ambulacral plates forming the mouth-papilUi), but on examination we find 

 that the structure of the actinal interambulacral plates is that of other 

 Starfishes. Seen from the interior on the actinal floor, the interbrachial 

 plate is sunk far below the level of the ambulacral groove; the inter- 

 brachial arches are reduced to the thickening produced by the junction 

 of the arms, which extend in wedge shape a short distance toward the 

 actinal ring ; the space in which the limestone canal is situated alone 

 connecting by a low ridge with the actinal ring. 



This is specially a West-Indian and Florida species. 



