328 -S-. WATASE. 



Pi.ATK XX'IX. — Serolis, Talorchedia, Camharus, Callincc/cs and 

 Limulus. 



Fig. 1. — Srroh's. Two ommatidia of Serolin; the one on the left 

 with tlic iiijiment cells enveloping the crystalline cone. The down- 

 ward extensions of the rhabdomeres reach to the retinal side of tlie 

 basement membrane, i (^ X 2) Zeiss. 



Fig. Iff. — SeroJis. Diagram of the Ommatidium — 

 a. Corneajion. 1. Cornea. 



h. Vitrella. 2. Crystalline cone. 



r. Retinula. 3. Rhabdomere. 



d. Hyaline cell. Pg. c. Pigment cell. 



Fig. lb.— Scrolls. Plan of the Ommatidium — 



1. Hyaline cell (d). 4. Corneagen (a). 



2. Retinula ((•). 5. Pigment cell (;;</. ()• 



3. Vitrella (i). 



Fig. 2. — Morphological diagram of the ommatidium of SeroUs — 



a. Corneagen. 1. Cornea. 



b. Vitrella. 2. Crystalline cone. 



c. Retinula. 3. Rhabdomere. 



d. Hyaline cell. 



Fig. 3. — Talorchestia. Ommatidium of Talorchestia. — Rt', upward 

 extension of the retinula Rl; this upward extension sometimes 

 reaches as far as the cornea, ^j. c. Narrow, non-pigmented packing 

 cells. J(nX4)Z. 



Fig. Za.— Talorchestia. Plan of the Ommatidia. 



Fig. 4. Cambarus. .Three ommatidia shown side by side. In c 

 the pigment cells (pg.c) completely envelop the crystalline cone. 

 X is the morphological lumen of the invagination. Ep is the epi- 

 thelial cell charged with light yellow pigment granules. * (I) X 2) Z. 



Fig. 5. Callinedcs. Two ommatidia shown side by side. Rhab- 

 domere (Rb) shows a fine striation. At the swollen end of the 

 retinula (i?0 yellow or brown colored globules are found. 



Fig. 5(1. — CalHnectes. Head of the retinulae more highly mag- 

 nified, and the rhabdomeres show slight enlargement at the terminal 

 portion. 



Fig. 6. — Limulus. Two ommatidia shown side by side, partly 

 schematic. TUe thick yellow-colored body is the chitinons covering 

 of the eye. L. lens-cone, fitting into the depression of the skin. At 

 the bottom of the depression, the essential part of tiie ommatidium 



