70 BULLETIN OF THE 



Plate XIX. 



a, mouth-shield; h, side mouth -shield ; c, jaws; d, mouth-papillae; d", tooth- 

 papillae ; e, jaw-plate ; 7i, under arm-plate ; i, side avm-plate ; n, genital scale ; 

 0, genital plate ; q, tentacle-scales ; r, tentacle ; y, outer articulating prominence of 

 an arm-bone ; /3, inner articulating prominence of an arm-bone. 



Fig. 487. Euryale asperum. Outer face of an arm-bone ; y, articulating promi- 

 nence. 5. 



Fig. 488. E. asperum. Inner face of next bone ; j3, articulating prominence of the 

 *' hour-glass" shape, i. 



Fig. 489. E. asjurum. Widened outer face of an arm-bone at a fork ; y, new 

 articulating prominence connecting with one new branch. |. 



Fig. 490. E. asperum. Inner face of next bone, split nearly in two, and bearing 

 two articulating prominences, /5. I . 



Fig. 491. Astroschema oligacies. A joint of the arm near its end, with the skin split 

 to show the thick, squarish side arm-plate (t), with the broken pieces above, which 

 answer to upper arm-plates ; the longer tentacle- scale, like a spine (q) ; and the 

 tentacle (r). ^. 



Fig. 492. Astrophyloii Agassizii. A portion of the mouth and under surface of the 

 disk in a very young specimen. . a, niadreporic radial shield ; h, large side mouth- 

 shield ; c, jaw ; d'\ tooth-papillie ; c, jaw-plate ; h, h, under arm-plate, divided in 

 three pieces ; t, large side arm-plates, meeting below ; 01, genital scale ; 0, genital 

 plate ; g, tentacle-scales or arm-spines. -V^. 



Fig. 493. A. Agassizii. Arm-joint near base of arm, showing the side arm-plate (t) 

 and the spine-like tentacle-scales (q). {. 



Fig. 494. A. Agassizii. Joint of a twig near end of arm, in profile, to show the 

 side arm-plate (i) and the hooked tentacle-scale (q). Above is the characteristic 

 double belt of grains, each bearing a hook. ^. 



Fig. 495. A. Agassizii. Tip of a twig, showing the side arm-plates encircling the 

 arm, and bearing little hooks. ^1". 



Fig. 496. Astrophyton Poiirtalesii. Portion of under surface of disk, showing the 

 narrow arm characteristic of this section of the genus. \. 



Fig. 497. Astrophytoii costosum. A portion of mouth and under side of disk, with 

 the skin removed to show the underlying hard parts; lettered like Fig. 492. \. 



Fig. 498. Astrophyton spinosrtm. Portion of under surface of disk, showing the 

 wide arm characteristic of this section of the genus. ^. 



Fig. 499. Euryale asperum. A part of mouth and surrounding parts with the 

 skin removed ; lettered as in Fig. 492. \. 



Fig. 500. E. asperum. .Joints near tip of arm, to show transition from hook-like 

 tentacle-scales {q) to those of a stiimpy shape. They are carried by the elongated 

 side arm-plates (i). Above is seen a large dorsal spine. ^-. 



Fig. 501. E. asperum. Joint close to tip of arm, in profile, to show the 

 gi-eatly elongated side arm-plate (?'), bearing two hook-like tentacle-scales [q). It 

 was this structure that Dr. Ludwig took for a pedicellaria. 



