ANATOMICAL NOTES ON THE ' COMET ' OF LINCKIA MULTIFOIiA, LAMARCK. 69 



regenerated arms proportionally. In other respects the small arms of a 

 ' comet ' are quite similar to the arms of a normal young. 



There are some difficulties in cutting open the thick and hard calcareous 

 integument of such a small Asteroid, without injuring iimer soft organs. 

 When the difficulty is overcome, the soft organs lying just below the aboral 

 wall appear as shown in Fig. -i taken from the older ' comet ' represented in 

 Fig. o. In the younger represented in Fig. I'these soft organs are about two- 

 thirds of the former in sizes, but similar in essential points. In the central 

 I)art we observe at first the roof* of the stomach, with muscular bands, by 

 which it is suspended from the aboral wall, and firm dendritic diverticula 

 with villi on their iimer surface. Fig. lo represents the muscular bands 

 as vyell as an outline of some (the upper half in Fig. 4) of the diverticula. We 

 observe, then, the loose lower portion of the stomach, with various folds on 

 the inner surface. From the uppei- part of this loose sac run out five pairs 

 of bhnd tubes with much larger cavity than the radial coeca of Astropecten''^'^ 

 or the hepatic coeca of Asteracttntheoii,'-''^ towards tips of the five arms 

 respectively. Each bears on each side a row of hepatic sacs, disposed side by 

 side (Figs. 8 and 9). These radial coeca are hung down from the aboral wall 

 by numerous tendinous strings. These strings are set in two rows along 

 the upper border in each coecum and therefore in four rows in each arm. 

 They are attached to the aboral wall of the latter along, the median longitu- 

 dinal axes (Figs. 8 and 9). The lower half of the coecum is membranous. 

 This membranous region is more or less folded as a preparation for a farther 

 dilation, and it is transversed by countless parallel lines (Fig. 9). Near the 

 distal end of the coecum this membranous area is step by step decreased and 

 th^. two rows of the hepatic sacs approach each other along the lower border. 

 The principal arm possesses, of course, the largest coecum with well develop- 

 ed hepatic sacs (compare Fig. 8 and Fig. 9), while the small arms are very 

 similar in all respects to the arms of a normal young. 



Fig. 5 represents a vertical view of the mouth part, as appears when 

 the stomach together with its appendages are cut off. This figure is taken 

 from the younger ^ comet ', but the view of the same parts is essentially 



* In this species tlie pyloric sac is hardly discernable from the lower cardiac pouch. 



