11 



Tlie heart lies just beneath the dorsal surface of the cai'apace, in the middle 

 line, behind the cervical groove. It is enclosed in a semi-transparent sack known 

 as the pericardium, which also contains blood. The cavity of the heart com- 

 municates with the cavity of the pericardium by three pairs of valvular openings 

 {ostia), so that blood can pass from the pericardium into the heart, but not in 

 the reverse direction. 



From the heart seven main arteries carry pure arterial blood to all parts of 

 the body. The ultimate ramifications of these arteries open freely into the 

 interstices of the tissues, whence the blood, after bathing the tissues, is at last 

 collected in vemus sinuses by which it is transported to the gills. After becoming 

 aerated in the gills, the blood passes by definite vessels into the pericardium and 

 so returns to the heart through the ostia in its walls. 



9. Of the Benal Excretory Si/ste 



m. 



The organs corresponding in function with the kidneys of higher animals 

 are a pair of tubular coiled green-glands. These are lodged in the antero-lateral 

 corners of the cephalothorax and open at a tubercle on the basal joint of the 

 antennal peduncle. 



10. Of tlie Central Nervous System. 



The central nervous system is of the ordinary Arthropod type. It consists 

 (L) of a large composite cerebral ganglion placed immediately in front of the 

 gullet and behind the eyes in the middle line of the b'ody, (2) of a continuous 

 ventral cord or chain of ganglia running along the whole length of the A^entral or 

 sternal aspect of the body, in the middle Une, as far as the penultimate abdominal 

 somite, the ganglia of the chain corresponding in a general way with the segmen- 

 tation of the body, and (3) of a pair of comnmsures which form a long narrow 

 collar round the gullet and connect the cerebral ganglion with the ventral chain. 



The cerebral ganglion, which is really double, gives off nerves to the eyes, 

 antennules, and antennae, and to the muscles which move those appendages. 

 The ganglia of the ventral chain send off nerves to all other parts of the body. 



[The Voluntary Muscles of Nephrops, like those of Arthropoda in general 

 are made up of multi-nucleate striped fibres, and their tendons are derived from 

 invaginations of the integument (exoskeleton)]. 



11. Of the Organs of Reproducticrn. 



These in the male are coiled tubular glands, which open upon the coxopodites 

 of the last pair of thoracic appendages (5th pair of legs). 



