336 PLATE XCI. 



The other three specimens are in the adult stage. 

 I divided the smallest of them longitudinally (it is 

 rather more than an inch in length), and found it to be 

 quite solid, without the least indication of internal 

 cavities. The greatest thickness of the largest speci- 

 men, the one represented by fig. 6, Plate XCI, does 

 not exceed seven lines. It is exceedingly fragile and in 

 the dried state it has quite a mealy feel to the touch. 

 When examined in the dried state by direct light the 

 upper surface is seen to be crowded with minute 

 cloacal organs among which there are a few of larger 

 size and conical shape. These large organs are com- 

 paratively smooth, while the numerous minute ones 

 are abundantly furnished with very long and slender 

 acerate defensive spicula. When these organs are in 

 a perfect condition these defensive spicula are so 

 abundant as to completely obscure the oscular surface, 

 and, in many cases, they are projected to a consider- 

 able extent beyond the distal extremity of the organ, 

 and they are so numerous, long, and slender as to 

 cause it very closely to resemble a camel's-hair pencil 

 in a dry condition, when viewed in Canada balsam 

 with a power of about 100 linear. No such defensive 

 appendages appeared on any of the few larger cloacal 

 organs that were observed. 



The large description of cloacaB did not exceed a 

 line and a half in diameter and rather more than three 

 lines in length ; the small ones varied from y^g- inch in 

 diameter to 3-^7 inch. The long, slender, defensive 

 spicula of these organs varied in length from -$ to 

 yjjo- inch, and their diameters rarely exceeded :nfoo 

 inch. These organs do not appear to assume any 

 definite direction in their procumbent state, but are 

 disposed in every possible direction, overlying each 

 other, frequently three or four deep. 



In one of the smaller cloacae, sectioned longi- 

 tudinally, the oscula were very distinctly exhibited by 

 direct light with a power of 100 linear on the inner sur- 

 face of the organ ; those near the distal extremity being 



