NOTES ON ECHINODERM MORPHOLOGY. 613 



arms. They often contain coagulum, and with a little prac- 

 tice may be readily distinguished from connective tissue. 



Professor Perrier gives us hardly any information respecting 

 the relations of the upper end of the ovoid gland. He admits 

 its connection with an oral ring in the Pentacrinoid, but he 

 does not say whether the functions of this ring are water- 

 vascular, blood-vascular, or the two combined ; and when he 

 says that the gland gives ofF no ramifications, he must have 

 forgotten Dr. Carpenter's description of its subdivision "into 

 diverging branches, of which one passes to each ray." This is 

 perhaps a stage which has not come under Professor Perrier's 

 observation. The radial branches of the ovoid gland develope 

 into the genital vessels which form a plexus beneath the ambu- 

 lacra of the disc, and eventually extend into the arms and 

 j)innules. Professor Perrier does not mention this plexus, 

 though it cannot well have escaped his notice ; nor does he 

 enter at all into the question of the ventral termination of the 

 ovoid gland in the adult. I regret his silence the more, as this 

 is esnecially a point on which more extended observations are 

 wanted. Both Ludwig and myself have experienced consider- 

 able difficulty with Ant. rosacea; but I have found A. 

 Eschrichti, A. carinata, Pentacrinus decorus, and 

 Promachocrinus kerguelenensis much more favorable 

 subjects of study. In the first-named species the ventral 

 branches of the central plexus end in a spongy organ with well- 

 defined limits, which has somewhat the appearance of a lym- 

 phatic gland. It is especially developed between the mouth 

 and anus, and is connected both with the oral blood-vascular 

 ring and with the genital vessels of the rays. An organ of 

 essentially the same character, though less prominent, occurs 

 in Ant. rosacea; and I had hoped for some account of it from 

 Professor Perrier, who, unfortunately, does not mention it. I 

 trust, however, that in the complete memoir which he is prepar- 

 ing he will remedy this omission. Meanwhile I am searching for 

 this spor.gy organ in as many different species as possible, and 



1 'Prrc. Enj-. Soc.,' vol. xxiv, p. 221. 

 VOL. XXIII. NEW SER. S S 



