SMALLWOOD. — POLYCERELLA ZOOBOTRYON. 



615 



three marginals are not so deeply colored as the first lateral and have 

 smooth outlines (Figure 5, l^, /"\ /"'). 



Verrill ('80, p. 386) gives the characteristics of the radula of the 

 genus Polycerella as follows : " Odontophore with six rows of teeth ; 

 median row absent ; inner laterals large, curved, with three denticles ; 

 two outer rows much smaller, simple 

 hook-shaped." Balch ('99, p. 150) 

 gives for P. davenportii, "Radula 

 almost as in P. emertonii Verrill 

 ('80-81, p. 387 ; '82, p. 548), rhachid- 

 ian tooth wanting ; pleurae strongly 

 hooked with accessory points, large ; 

 uncini two, sickle-shaped. Formula 

 2-1-0-1-2." The genus characters 

 of the teeth should be modified, both 

 in reference to the number of rows 

 of teeth and to the shape of the outer 

 laterals, so as to read as follows : — 

 Odontophore with six to eight rows 

 of teeth, median row absent, inner 

 laterals large, slightly curved ; outer 

 rows much smaller, may or may not 

 be curved. 



The esophagus (Figures 3, 4, oes.), 

 as it arises from the dorso-posterior 



angle of the pharynx, has a diameter of 15 micra, which it retains 

 until it expands into the stomach. It passes dorsally and poste- 

 riorly 100 micra, until it reaches the anterior surface of the posterior 

 genital mass, where it turns abruptly to the right, entering the liver 

 and passing through it for a short distance. As it emerges fi-om the 

 liver, it expands into the stomach-intestine (Figure 3, ga.-int.), the 

 anterior extremity of which is beneath the renal chamber. The stom- 

 ach-intestine is dorsal to the posterior hermaphroditic mass, and it 

 reaches its greatest width near its anterior end, becoming gradually 

 smaller until the anal opening is reached. There is no differentiation 

 into stomach and intestine. The stomach-intestine receives two sepa- 

 rate bile ducts, each connected with an independent bile sac. The 

 duct of the smaller sac opens into the floor of the anterior end of the 

 stomach-intestine, while that from the much larger bile sac opens into 

 the posterior third of the organ. 



A single pair of salivary glands, each about 28 micra long and 12 

 micra in diameter, opens into the posterior part of the pharynx just an- 



FiGUKE 5. l^, First lateral tooth; 

 I n, I "I, II ^, second, third, and fourth 

 lateral teeth drawn under one-sixth 

 in. objective and one in ocular, with 

 the aid of a camera lucida. 



