The heart (16) surrounded by the pericardial sinus lies above the intestine. The pericardium is shown between the heart and the intestine. The ostia (17) of the heart and the origins of the four lateral arteries (19) are indicated; the frontal artery (13) and the aortic arches (14) curving down to the brain, arise from the anterior end of the heart; the superior abdominal artery and the opening of the collateral artery into it are shown. The brain surrounding the oesophagus is seen in side view upon the neural side of the endosternite (34). The ventral cord (35) passes through the occipital ring into the abdominal region. The anterior commissure (3), with the three rostral nerves (2) innervating the rostrum, or labrum, and four of the post-oral commissures, are represented. The cheliceral nerve with the small external pedal branch is shown entire, but the next five neural nerves are cut off. The chilarial nerve, the opercular nerve, and the five branchial nerves, enter their respective appendages, the two former passing through the occipital ring. From the fore-brain the three olfactory nerves (5) pass anteriorly to the olfactory organ; the median eye-nerve (10) passes to the right of the proventriculus (12) to the median eyes (11); the lateral eye-nerve (7) passes forward and is represented as cut off opposite the proventriculus. The lateral nerve (9) or first haemal nerve is also cut off just beyond the point where it fuses with the second haemal nerve (8). The stomodaeal nerve (6) ramifies over the oesophagus and proventriculus. The second haemal nerve (8) passes to the anterior extremity of the carapace; its haemal branch is cut off opposite the proventriculus. An intestinal branch arises from near its base and disappears behind the anterior cornu of the endosternite. The next three haemal nerves (36) are cut off close to the brain, and the following nine haemal nerves are cut off beyond the cardiac branches. The fifteenth haemal nerve (29) is cut off beyond its branch to the telson muscles. Both branches of the haemal nerve are represented extending into the telson (25).