90 WILLIAM PATTKN. 



PLATE 1. 



Fig. 1. — Longitudinal section through the anterior wall of one of the stout 

 gustatory spines of the mandibles, showing the cuticular canals, each con- 

 taining a chitinous tubule. 



Fig, 2. — A gustatory spine from the mandibles, seen from its anterior sur- 

 face, and showing the lines of pores into each of which runs a chitinous 

 tubule. X 30. 



Fig. 3. — Third appendage on right side of an adult female, seen from in 

 front, with the anterior wall removed, and showing the nerve to the appen- 

 dage with its mandibular branches. Natural size. 



Fig. 4. — Nucleated end of one of the gustatory cells of the mandibular 

 spines, showing the peculiar yellowish -brown granules that are sometimes 

 found in these cells. Isolated by Bela Haller's fluid. 



Fig. 5. — Distal end of a gustatory cell from the mandibular spines, show- 

 ing fibrillar structure of the cell body and the spindle with its internal cone 

 of flbrillse, each fibrilla having an enlargement at the base of the spindle, and 

 all converging toward the apex, where they unite to form the axial nerve- 

 bundle that runs outwards through the chitinous tubule. X about 2000. 

 Macerated in Haller's fluid and stained in acetic acid carmine. 



Figs. 6 and 7. — Spindles from gustatory cells of mandibular spine, showing 

 the partly detached nerve-cells, and the projecting axial nerve-bundle, which 

 in Fig, 7 is broken up into its constituent flbrillse. Haller's fluid and methyl 

 green. 



j'lg, 8. — Very young gustatory bud from the inner mandible, showing the 

 circle of refractive rod-like plates and the single ganglion-cell with its flbrous 

 prolongation. 



YiG. 9. — Two sense buds from the olfactory organ, showing the chitinous 

 tubule, central ganglion-cell, and the nerve-plexus. Slightly diagrammatic. 



Fig. 10, — Three cuticular canals from the base of a mandibular spine. 

 A. Larger canals with short spine in a saucer-shaped depression at the 

 summit. May be one of the temperature organs. B. Ordinary gustatory 

 canal, c. Same, with a few bead-like globules in the chitinous tubule. 



Fig. 11. — Surface view of the cuticle from the chelae of the walking appen- 

 dages of a young Limulus about 8 inches long, showing the two kinds of 

 sensory pores, the gustatory pores at ff. o., and the temperature organs at 

 t. 0. 



Fig. 12. — The nucleated portions of two gustatory cells from the mandi- 

 bular spines, showing that they are formed of two imperfectly fused cells 

 similar to the double ones described by the author in ' The Eyes of Molluscs 

 and Arthropods.' 



