TYPE ANNELIDA. 



229 



which each ring of the middle region of the body bears an 

 appendage which functions as a gill. In another marine form, 

 Pontobdella, large warts occur on certain rings, which prob- 



f I/" 



Efv." ... ;,^24 



H^-^^^439 



gc- 



XE ( '-^ 



(TTM:;i-.''i 



^E^44 



an 



FlG. 106. ANTERIOR AND POS- 

 TERIOR EXTREMITIES OF Ma- 



crobdellu sestertia (after WHITMAN). 



an auus. 



fo opening of oviduct. 



gc copulatory glands. 

 mo openiug of vasa deferentia 



oc eyes. 



p = nephridial pores. 



sp = sense-papilla. 

 1-100 = anuuli. 

 i-xxv = uietauieres. 



lv 



ne 



FIG. 107. DIAGRAMS TO SHOW AR- 

 EANGEMENT OF BLOOD-SINUSES OF (A) 

 Hirudo, (B) Clepsine, AJSID (C) Nephelis 

 (after BOURNE). 



al = digestive tract. 

 c = coelom. 

 ds = dorsal sinus. 

 Is and lv = lateral sinus or vessel. 

 n and nc ventral uerve-cord. 

 ne = uepbridium. 

 ov = ovary. 

 te = testis. 

 vs ventral sinus. 



ably are mainly respiratory in function, being richly supplied 

 with blood-vessels. 



The exterior of the body is covered by a cuticle, beneath 

 which lies the hypodermis. The muscular tissue which un- 

 derlies the hypodermis consists, as in other Annelida, of layers 



