440 MR. HERBERT L. HAWKINS ON 



ri. LIX. 



Last larval stage (3Ii/sis stage) of Limnocarid ma parvula Clm. 



Fig. 1. Dorsal view of the larva. 



2. Same larva, viewed from left side. 



3. Antennula. 



4. Antenna. 



5. Anterior lip. 



6. Right mandible and masticator^' part of left. 



7. Anterior maxilla. 



8. Posterior maxilla. 



9. Maxilliped of 1st pair. 



10. Maxilliped of 2nd pair. 



11. Maxilliped of 3rd pair. 



12. Cheliped (exopodite not fully drawn). 



13. Pereiopod of 1st pair (exopodite not fully drawn). 



14. Pereiopod of last pair. 



15. Pleopod of 1st pair. 



16. Pleopod of 2nd pair. 



17. Extremity of last caudal segment, with telson and left uropod ; dorsal view. 



Pi. LX. 



First post-larval stage of Limnooaridina parvula Clm. 



Fig. 1. Dorsal view of the specimen. 



2. Same specimen, viewed from left side. 



3. Antennula. 



4. Antenna. 



5. Mandible. 



6. Anterior maxilla. 



7. Posterior maxilla. 



8. Maxilliped of 1st pair, 



9. Maxilliped of 2nd pair. 



10. Maxilliped of 3rd pair. 



11. Cheliped. 



12. Pereiopod of 1st pair. 



13. Pereiopod of last pair. 



14. Pleopod. 



15. Outer part of telson, 



25. The Classification, Morphology, and Evolution of the 

 Echinoidea Holectypoida. By Herbekt L. Hawkins, 

 M.Sc, F.Gr.S, ; Lecturer in Geology, University College, 

 Reading*. 



[Received November 16, 1911 : Read March 5, 1912.] 

 (Text-figures 54-60.) 



Contents. Pao-e 



I. Introduction 440 



n. History of Past Classification 44.2 



III. The Revised Classification 445 



IV. Comparative Morphology 454 



V. The Internal EvolutiorT'of the Group 481 



VI. The External Relationships 487 



VII. Summary 494 



VIII. List of Literature consulted 495 



I. Introduction. 



"Within the limits of a single class, it would be difficult to find 

 greater contrasts than those which distinguish the various orders 



* Communicated by Dr. Henex Woodwaed, F.R.S., V.P.Z.S. 



