JOURNAL OF MICROSCOPICAL SCIENCE. 



EXPLANATION OF PLATES XI AND XII, 



Illustrating Mr. P. Herbert Carpenter's paper on " The 

 Minute Anatomy of the Brachiate Echinoderms." 



The following letters denote the same parts in all the figures of both 

 Plates : 



a. b. Aboral blood-vascular ring ; a. e. ambulacral epithelium ; a. p. axial 

 perihsemal canal; b. radial blood-vessel; b,/. its branches to the sucking 

 feet ; b. m. buccal membrane ; C. ccelom ; c. a. ccelom of the arms ; c. p. 

 central plexus ; E. epithelium of body ; 0. gut ; g. blood space around 

 genital gland ; g. v. genital vessel ; i. p. inner oral perihsemal ring-canal ; 

 L. lip ; M. mouth ; m. i. interradial muscle ; n. radial trunk of the ambu- 

 lacral nervous system ; n. r. its oral ring ; o. b. oral blood-vascular ring ; 

 0. p. outer oral perihsemal riug-canal ; ov. ovary ; ph. perihsemal space ; 

 r. p. radial perihsemal canal ; s. annular septum in oral perihsemal canal ; 

 s. c. stone canal ; to. radial water- vessel ; w. r. water-vascular ring. 



The following colours are used for the same parts in both Plates : 



Red, blood-vascular system ; yellow, ambulacral nervous system ; green, 

 water-vascular system, 



PLATE XI. 



Anaiomy of the Starfishes and Ophiukids. 



All the figures in this Plate are copied from Ludwig,with slight altera* 

 tious in the colouring. 



Pig. 1. — Diagram of the blood-vascular system of an Ophiurid, as seen 

 from the dorsal side. The contours of the disc and arms are indicated by 

 dark lines, and the radial vessels by dotted lines, 



a. b^ Interradial portions of the aboral blood- vascular ring, which 



rest on the mouth shields ; a. b^ descending limbs of this ring at the 



sides of the rays ; a. b^ radial portions of the ring beneath the radial 



shields ; b. c. bursal cleft. 



Pig. 2. — Diagram of the blood-vascular system of a Starfish, based upon 



preparations of Astropecteii mirantiacus. The positions of the falciform 



folds are indicated by | |. 



p. b. Plexiform vascular bundles, proceeding to the walls of the 

 stomach ; x. dorsal terminal portion of the central plexus. 



Pig. 3. — Diagram of the structure of a Starfish arm. The outer wall of 

 the arm is too thin in proportion to the structures in the ambulacral groove, 

 the relative size of which is somewhat exaggerated. On the left of the 

 dotted line x y, the section passes through the middle of a vertebra ; while 

 on the right, the section passes between two vertebras. The pyloric caecum 

 is omitted from tlie left side, and the genital gland from the right. The 

 upper and lower transverse muscles of the vertebrse are represented on the 

 left side. The inner layer of the integument is simply shaded, and the outer 



