DORIS. 



simple teeth (figs. 8, 9). There is no central tooth in this species, any more than in 

 D. Johnstoni or B. coccinea, in both of which the teeth are likewise simple ; but in the former 

 of these the outer teeth suddenly become excessively attenuated, and in the latter attenuated 

 and elongated. B. Johnstoni has twenty-four rows, each of about fifty teeth. The tongue of 

 D. repanda is provided with a central tooth (fig. 10«) bearing four recurved denticles, and 

 has the lateral teeth (figs. 10, 11) with regularly serrated sides. This species has sixty-eight 

 rows, of thirty-seven teeth each. In our second section, represented by B. bilamettata and 

 B. aspera ; and in our third section, typified by B. pilosa, the tongue (Fig. 3 /, and Fig. 4) is 

 narrow and strap-shaped, being composed of only two rows of teeth, and these placed 

 longitudinally. In these species, therefore, this organ, having a wedge-shaped muscular 

 support (fig. 3£), has a general resemblance to that of Bolls. It is nevertheless essentially 

 formed as in other Dorides, and has the posterior portion tubular (fig. 4 b). The two rows are 

 of lateral teeth, the central ones being entirely deficient. There are twenty-eight teeth (fig. 5), 

 in each row in D. pilosa, with the sides minutely denticulated. The teeth are equally numerous 

 in B. bilamettata, but the sides are plain. 



Besides the tongue, some of the Dorides are provided with a spinous prehensile collar 

 (fig. 3 h), situated at the entrance of the buccal apparatus, and placed in a vertical position on 

 what may be termed the buccal lip {(/). This collar is of nearly uniform breadth in B. repanda, 

 and is densely covered with minute, curved, bifid spines. In B. pilosa it is provided with 

 similar spines (PL 2, figs. 3, 4, 5), and is divided into two lateral portions (fig. 2 b, b), broad 

 below, and tapering to five points above. These two portions of the collar have, intervening 

 between them below, two minute triangular processes (c) of a horny plate (fig. 6), which is 

 buried in the buccal lip, having only the free points exposed ; these are inclined upwards and 

 forwards. This plate with its processes may, perhaps, be looked upon as the homologue of 

 the jaws in Eolis ; though this relation may admit of doubt, nevertheless it appears to be 

 accessory to the prehensile action of the collar. The prehensile collar and jaws of B. sub- 

 quadrata closely resemble those of B. pilosa. B. bilamettata is provided with a similar horny 

 plate and processes, but much less developed, and the collar is very indistinct, having the 

 surface only roughened with dense, minute wrinkles. B. coccinea is also furnished with a 

 spinous prehensile collar. These five are the only species in which we have detected this 

 curious organ, which is probably a compensation for the deficiency of well-developed jaws. 



A pair of salivary glands (fig. 1 //), generally in form of long slender tubes, open into 

 the mouth, one on each side of the oesophagus ; B. bilamettata has these tubes replaced by a 

 follicular mass (PL 1, fig. 13 e) attached to the posterior part of the buccal apparatus ; and in 

 B. pilosa they (fig. 12 d) are enlarged and folliculated at their bases. 



The oesophagus (PL 2, fig. 1 b) in B. tuberculata is a nearly straight tube passing from 

 the posterior dorsal aspect of the buccal organ ; it is slightly enlarged after passing through 

 the nervous collar, and is then continued on, of equal diameter, to the posterior or cardiac end 

 of the stomach, which (PL 1, fig. 2 b, and PL 2, fig. 1 c) is a very large pyriform pouch, 

 having the inner surface minutely corrugated. It lies on the left side of the body, and has the 

 narrow posterior end resting between the lobes of the liver. Here the biliary fluid is poured 

 in by a large canal (PL 2, fig. ly), and at this part, too, a small pancreatic organ (?) gives its 

 secretion to the stomach by the side of the oesophagus. The intestine (d, d) leaves the 



