PLATE V. 



UlNTACRINUS SOCIALIS. ArMS AND PiNNULES, AND InTEEBEACHIAL ArEAS. 



Figs. 1 to 4. A series of specimens from maximum to small size, showing form and propor- 

 tions of arms, pinnules, and brachials in individuals of various stages of 

 growth. Specimens Nos. 117, 3, 78 a, and XX a. 



Fig. 5. Medium specimen, dicyclic ; with 3 and 5 plates in interbrachial areas. 



No. 247. 

 (See photograph of base of this specimen enlarged, PI. VII., Fig. 3, infrn.) 

 " 6. Large monocyclic specimen; showing variation of 7 to 14 plates in iBr areas. 



No. 25. 

 " 7. Maximum specimen, dicyclic; showing profuse development of iBr and illBr 



plates. No. 41. 



" 8. Specimen laterally compressed; showing the fixed and proximal free pin- 

 nules, and the anal tube in natural position. No. 130. 

 " 9. Pinnule from upper part of arm ; showing dice-box shape of pinnules, x 5. 

 (All figures not otherwise noted natural size. Figs. 1, 2, 3, 4, 6, 7, 8 by 

 Chapman; 5 and 9 by Mrs. Ricker.) 



