THE PYCNOGONIBS. 71 



this clear stain able portion is at the sides and not at the ends, 

 for a thick protoplasm lies between the rods. Finally, we find 

 similar transparent and perhaps more solid parts of the retinal 

 elements of other eyes belonging to quite different groups, as in 

 the Ascidians and in the Mollusks (see Pecten), and certainly 

 in the latter group no one will imagine them chitinous or any 

 homologue of chitin. 



LIST OF WORKS REFERRED TO. 



1. Balfour. Notes on the Development of the Araneina. Quart. 

 Journ. Micr. Sci., vol. XX, 1880. 



2. Balfour. Elements of Embryology. 1880. 



3. Clans. Crustaceen-Systems. Wien, 1876. 



4. Dohrn, Ant. Neue TJntersuchungen liber Pycnogoniden. 

 Mitth. a. d. Zool. Stat. Neapel, Band I, 1879. 



5. Dohrn, Ant. Die Pantopoden des Golfes von Neapel. Fauna 

 und Flora des Golfes von Neapel. Band III, 1881. 



6. Hatcheck. Beitrage zur Entwicklnngsgeschichte der Lepi- 

 dopteren. Jena, Zeit. Naturwiss., No. 11, 1877. 



7. Heider, K. Ueber die Anlage der Keimbliitter von Hydro- 

 philus piceus. Abh. d. K. Preuss. Akad. d. Wiss. Berlin, 1885. 



8. Midler, Fritz. Fur Darwin. Leipzig, 1864. 



9. Metschnikoff, E. Entwicklnngsgeschichte des Chelifer. Zeit. 

 f. wiss. Zool., XXI, 1871. 



10. Schimkewitsch. Zur Entwicklungsgeschichte der Araneen. 

 Zool. Anz., VII, 1884. 



11. Schimkewitsch. Etude sur le developpement des Araignees. 

 Archiv de Biologie, 6, 1887. 



12. Sedgwick, A. A Monograph of the Development of Peripatus 

 Capensis. Stud. Morph. Lab., Camb., IV, Pt. I, 1888. 



13. Semper. Ueber Pycnogonida und ihre in Hydroiden schma- 

 rotzenden Larven-formen. Arb. a. d. Zool. Zoot. Inst. Wiirzburg, 1, 

 1874. 



14. Wheeler. The Embryology of Blatta Germanica and Dory- 

 phora Decemlineata. Jour. Morph., Ill, 1889. 



15. Wilson, E. B. The Pycnogonida of New England and Adjacent 

 Waters. U. S. Commissioner's Report, Pt. VI, 1878. 



