112 



MARINE ANIMALS OF MASSACHUSETTS BAY. 



completely, and proceed leisurely to suck out the animal from its 

 shell. Cutting open any one of the arms we may see the yellow 

 folds of the stomach pouches which extend into each ray ; within 

 the arms, extending along either side of the upper surface, are 

 also seen the ovaries, like clusters of small yellow berries. Im 

 mediately below these, along the centre of the lower floor of each 

 ray, runs the ridge formed by the ambulacral furrow, and upon 

 either side of this ridge are placod the vesicles, by means of 

 which the tentacles may be filled and emptied at the will of the 

 animal ; the rest of the cavity of the ray is filled by the liver. 

 The mouth, which is surrounded by a circular tube, is not fur 

 nished with teeth, as in the Sea-urchin ; but the end of each 

 ambulacral ridge is hard, thus serving the purpose of teeth. 



Fig 146. 



Cribrella. (Cribrella oculata FORBES.) 



Our coast, as we have said, is not rich in the variety of Star 

 fishes. We have two large species, one of a dark-brown 

 color (Fig. 132), the Astracanthion berylinus, and the other, 

 the A. pallidus, of a pinkish tint ; then there is the small Cri 

 brella, inferior in structural rank to the two above mentioned. 

 (Fig. 146.) This pretty little Star-fish presents the greatest 



variety of colors ; some are 

 dyed in Tyrian purple, others 

 have a paler shade of the same 

 hue, some are vermilion, others 

 a bright orange or yellow. A 

 glass dish filled with Cribrellas 

 might vie with a tulip-bed in 

 gayety and vividness of tints. 

 The disk of the Cribrella is 

 smooth, instead of being cov 

 ered, like the larger Star-fishes, 

 with a variety of prominent ap 

 pendages. The spines are ex 

 ceedingly short, crowded like 

 little warts over the surface. It is an interesting fact, illustrat- 



Fig. 146. Cribrella from above 5 natural size. 



