242 



MORPHOLOGY OF INVERTEBRATE TYPES 



nephridial portion of the posterior vena cava and the nephridial 

 arm of the anterior vena cava is a distinct constriction. 



The branchial 

 hearts, one at the 

 base of each gill, 

 are inclosed each 

 in its own pericard 

 which is simply a 

 rs.rc pouch of the cce- 



C.7' 



v.p.s 



cl 



c-v 



lome. Each heart 

 has two openings. 

 One opening ad- 

 mits the blood 

 from the nephrid- 

 ial arm of the an- 

 terior vena cava 

 \ / and is protected 



// by two semilunar 



FIG. 48. Diagram of the excretory system of valves. The other 

 Sepia officindis after Vigelius (from Encyclopaedia ODenm g j eac j s mto 

 Britannica, Cephalopoda, Fig. 29). The nephridial 



sacs are supposed to have their upper walls removed, the branchial ar- 

 v. c, vena cava; r. d. v. c, right descending branch of t er y an( J h as a 

 the same; r. s. v. c, left descending branch of the . . 



same; v. b. a, vein from the ink-bag; v. m, mesen- valve consisting of 

 teric vein; v. g, genital vein; v. a. d, right abdominal four tubercles. At- 

 vein; v. a. s, left abdominal vein; v. p. d, right pallial ^ acne( j j- o each 

 vein; v. p. s, left pallial vein; c. b, branchial heart; 



x, appendage of the same; c. v, capsule of the branchial heart IS 

 branchial heart; />, external aperture of the right a lymphatic or per- 

 nephridial sac; y, reno-pericardial orifice placing the . _, , j -, i 

 left renal sac or nephridium in communication with 



the viscero-pericardial sac, the course of which below majority of the 

 the nephridial sac is indicated by dotted lines; y f , the smaller veins car- 

 similar orifice of the right side; a. r, glandular renal . 

 outgrowths; u>. k, viscero-pericardial sac (dotted r y m S the blooa 

 outline). from various or- 



gans are tributaries of the venous system of the anterior vena 

 cava. (They are not shown in Fig. 47.) 



