Introduction to A n imal Morphology. 2 o i 



oesophagus may be long (Haementeria), or short, but 

 the stomach is long, with alternate dilatations and 

 contractions Pontobdella), or with lateral caeca; ofthese 

 Clepsine has six, llirudo nine, Piscicola ten, Aulaco- 

 stomum only two. These may be branched as in Clep- 



reminding one of a dendroccelous Turbellarian. 

 The pylorus is surrounded by a sphincter, and the 

 ^ ht intestine runs often between the two hindmost 

 caeca, which are longest, the only ones present in 

 Aulacostomum. The intestine may also have caeca 

 (Clepsine} and a pre-anal dilatation (Piscicola). The 

 anus is dorsal above the hinder sucker. 



The circulatory system contains often red blood, 

 the colour residing in the fluid, seldom in the corpuscles. 

 In most, the blood flows in the nearly obliterated 

 body cavity which here exists as a system of sinuses. 



' may form two lateral pulsating vessels, and a 

 median sinus divided by the viscera into dorsal and 

 ventral vessels, which in Clepsine and Piscicola have 



3, but these around the pharynx are continuous 

 as a vascular ring, and freely anastomosing ; lacunary 

 from these vessels complicate their relations ; 

 some ofthese are contractile spaces in Nephelis. These 

 lacuna* permeate freely the spongy derm is and mus- 

 cular layers Respiration is dermal, and the lateral 



Jar organs in Hranchellion and O/<>l>ranrhus 

 be tur breathing purp< < 



organs are tubes with glandular 

 wall-. : alon^- tin- ventral 



aspect, varying from 1 .m hiobdriia to seventeen 



llirudo , either closed internally, or opening within 



, funnel-shaped orifice, while the outer 



era! wart A primitive set of 



