47 



i. Intestine. 



i 1-4. Entapophysial pits of thoracetron. 



k. Terminal spine of the ocular or medilateral 



ridge of the carapace. 

 /. Anterior hepatic duct. 

 m. Posterior hepatic duct. 



in 1-6. Marginal articulated spines of thorace- 

 tron. 



n 1-7. Marginal spinous angles of thoracetral 



segments. 

 n. Liver. 

 n". Hepatic lobe, partially injected from the 



duct. 

 0. Dilated beginning of intestine. 

 s. Stomach. 

 t, t. Fasciculiof 'depressoresthoracetri'muscles. 



Fig. 2. Heart and vessels, with parts of ovaria, in situ, viewed from above. 



A, B, c, as in fig. 1. 



a. Heart. 



b. Part of pericardial sinus. 



b'. Part of pericardial sinus laid open. 



c. c. Ostia venosa. 



e, e. Neural arteries. 

 f,f. Epimeral arteries of cephalctrou. 

 g,ff'. Epimeral arteries of thoracetron. 

 h. Ocellar artery. 



i 1-6. Entapophysial pits of thoracetron. 



n. Medilateral vein and sinus of cephaletron. 



0. Oviduct. 



p. Anterior thoracetral vein. 



q. ^Middle thoracetral vein. 



r. Posterior thoracetral vein. 



s. Median thoracetral vein. 



u, u. Fasciculi of the ' levatores telsoni.' 



Fig. 1 



Plate II. 



Limulus polyphemus. 



Longitudinal section, with side view of the nervous system, the heart laid open, and the alimentary 

 canal in situ. The explanation of the parts is given in the outline of this figure in Plate II a. 

 2. Longitudinal section of cephaletron and fore part of the alimentary canal, showing the relations 

 to the mouth of the cephaletral limbs. The explanation of the parts is given in the outline of 

 this figure in Plate II a, which also includes figures 3, 4, 5. 



6. Anterior view of the head of Julus terrestris, dissected to show the cephalic or superoesophageal 



lobes, and the nerves to the eyes, antennae, and mandibles (magn. 6 diameters) . 



7. Upper view of the brain and nerves, with the beginning of the ventro-chordal part of the neural 



axis of Julus terrestris (magn. 6 diameters). 



8. Upper view of the cephalic lobes, with the optic nerves and disposition of the beginning of the 



stomato-gastric system of nerves upon the corresponding part of the alimentary canal of Julus 

 terrestris (magn. 6 diameters). 



Plate II a. 



Limulus polyphemus. 



Fig. 1. Outline of figure 1, Plate II., giving a side view of heart, alimentary canal, and nervous system. 

 A, B, c, I & a 1, as in PI. I. in. Antenna. 



a'. Under or vaulted surface of cephaletron. iv. Mandibula. 



b". Anal segment of thoracetron. v. Praemaxilla. 



II. Antennula. 



VI. Maxilla. 



