506 PROF. OWEN ON THE AMERICAN KING-CRAB. 
PLATE XXXIX. 
Limulus polyphemus. 
Fig. 1. Nervous system, from the upper or dorsal aspect. 
a. Supercesophageal mass. 
B. (Esophageal ring. 
na. Ocellar nerve. 
na. Ocular nerve. 
n3. Gastric nerve. 
n4. lst Epimeral nerve. 
n8. 4th Epimeral nerve. 
n9. 5th Epimeral nerve. 
n 15. llth Epimeral nerve. 
n16. 12th Epimeral nerve. 
n 17. 13th Epimeral nerve. 
n18. 14th Epimeral nerve. 
n19. 15th Epimeral nerve. 
pl. Pleonal plexus. 
(The preparation is No. 1303 c in the Physiological Series of the Museum of the Royal College 
of Surgeons.) 
Fig. 2. Left branchiigerous limb, with attached branchia. 
a. Tract of efferent branchial vessels. 
Fig. 3. Branchial lamella; a, efferent plexus. 
All the figures, save where otherwise stated, are of the natural size. 
Woonctts. 
Fig. 1. Cell-egg, with yolk-cells developing: magnified 130 diameters. 
Fig. 2. Impregnated egg after disappearance of primitive cells: magnified 30 diameters. 
Fig. 3. Section of egg-coat and germ-trace: magnified 130 diameters. 
Fig. 4. Ovum with embryo-trace: magnified 10 diameters. 
Fig. 5. Ovum with embryo further developed: magnified 10 diameters. , 
Ovum with embryo, under-view : magnified 10 diameters. 
Embryo Limulus, just before hatching, back view: magnified 13 diameters. 
Newly hatched Limulus: magnified 9 diameters. 
Nauplius, or young of Apus cancriformis : magnified. 
Fig. 10. Nauplius, or young of CHERS quadricornis : magnified. 
Fig. 11. Zoea, or larva of Peneus 
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