CIRCULATORY SYSTEM 139 



c, The roots of the arteries are rather small and trans- 



parent, and hence difficult to see. They arise 

 from the two ends of the heart, and should be 

 seen at the present stage in the dissection, though 

 the arteries themselves are best seen in an in- 

 jected specimen, and will be described later 

 (p. 150). 



i. From the anterior end of the heart arise a median 

 ophthalmic artery and a pair of antennary 

 arteries ; and behind and below these a pair 

 of hepatic arteries. 



ii. From the hinder end of the heart arises the large 

 median superior abdominal artery, and imme- 

 diately below this the large median sternal 

 artery, which latter can be better seen at a 

 later stage. 



d. The alas cordis are three pairs of fibrous bands 



which hold the heart in position by connecting it 

 with the walls of the pericardial sinus. 



FIG. 27. Astacus fluviatilis, var. nobilis. Dissection of a male from 

 the right side. The right side of the body -wall with its appendages, 

 and the right side of the ossophagus, stomach, and mid-gut, have 

 been removed, (c. H. H.) 



A, endophragmal skeleton. AA, antennary artery. ATI, auditory sac. 

 B, basipodite of the tenth appendage. BD, aperture of the bile-duct into the 

 meseuteron. C, cardiac chamber of the stomach. CM, caecum. CO, cardiac 

 ossicle. CP, carpopodite of tenth appendage. CP 9, carpopodite of ninth 

 appendage. CX, coxopodite of tenth appendage. D, dactylopodite of the 

 same. DA, dorsal abdominal artery. E, eye. G 1, supra-oesophageal gang- 

 lion. Gr 2, sub-oesophageal ganglion. G 3, second post-oesophageal ganglion. 

 G 8, last thoracic ganglion. G 14, last abdominal ganglion. H, right lateral 

 ostium of the heart. HA, hepatic artery. I, proctodoeum. IS, ischiopodite 

 of the tenth appendage. K. kidney. L, liver. LT, lateral tooth. M, mero- 

 podite of the tenth appendage. MS, metastoma. MT, median tooth. 

 M 8, meropodite of the eighth appendage. N 1, N 2 etc. endopodites of first, 

 second, etc. appendages. OA, ophthalmic artery. OC, left para-cesophageal 

 connective : the greater part of the right one has been removed. O B, resophagns. 

 PL 16, pleuron of the sixteenth segment. PO, pyloric ossicle. PPO, pre- 

 pyloric ossicle. PR, propodite of the tenth appendage. PTO, ptero- 

 cardiac ossicle. PY, pyloric chamber of the stomach. P3, P 4, P5, pro- 

 topodites of the third, fourth, and fifth appendages. R. rostrum. SA, sternal 

 artery. S 16, sternum of the sixteenth segment. T, testis : the right anterior 

 lobe has been removed. T 16, tergum of the sixteenth segment. TJ, ureter. 

 TJA, aperture of the ureter. UCO, urocardiac ossicle. VA, ventral abdo- 

 minal artery. VD, left vas deferens : the right one has been cut off short. 

 VDA, aperture of the left vas deferens. XI, X2, etc. exopodites of first, 

 second, etc. appendages. ZO, zygocardiac ossicle. 14, the fourteenth appen- 



