ON THE MORPHOLOGY OF THE COMPOUND 

 EYES OF ARTHROPODS. By S. WATASK, Fellow of 

 the Johns Hopkins University. With Plates XXIX-.XXXV. 



Contents. pa^e. 



I. Introduction 287 



II. Morphology of the Oinmatidiura. 



a. Serolis 390 



b. Talorcheslia 595 



c. Cambanis 297 



d. Homarus 299 



e. Callinecles 299 



III. Compound (Lateral) Eye of Limuhis. 



a. General Sketch of the Compound Eye 301 



6. Structure of the Ommatidium 303 



c Development of the Compound Eye 307 



rV. Phylogeny of the Ommatidium 318 



V. Summary 323 



VI. Appendix : The Compound Eye of Echinoderms 324 



VII. Explanation of Figures 337-334 



I. — Introduction. 



Early in the spring of 1888, Prof. W. K. Brooks kindly placed 

 at my disposal a valuable set of specimens of Liimdus^ with a 

 suggestion that I should work on the eyes in order to continue 

 the research upon which the late Dr. A. T. Bruce was engaged 

 at the time of his death. 



Through the kindness of Prof. M. McDonald, the United States 

 Commissioner of Fish and Fisheries, I was enabled to continue 

 my work on the subject during the summer of the same year at 

 the Woods Holl Laboratory of the Fish Commission, where the 

 fresh specimens for the study of Lirnulus at all stages of develop- 

 ment may be obtained without ditEculty. To these gentlemen 

 are d\ie my sincere thanks and gratitude; through tlieir kind- 

 ness and encouragement I have been eiiublod to prusicnte my 



'These specimens were mostly preserved by Dr. J. C. Ilemmeter, when the 

 Chesapeake Zoological Laboratory was in session at Beaufort, N. C, in 1886. 

 They were in an excellent state of preservation. 



