EOLIS. 



Sec. 4. Branchial papilla in a single longitudinal row on each side. Tergipes, Cuvier. Type, 

 E. despecta. 



The body is linear ; the dorsal tentacles smooth, the oral tentacles very short ; and the 

 sides of the foot rounded and not produced. 

 Spawn kidney-shaped. 



In sections 1 and 2 the auditory capsules contain numerous otolithes ; in section 3 

 they contain only one otolith e each.* 



These sections run imperceptibly into each other, but in general their characters are 

 pretty well marked. The branches of the digestive system undergo a modification in each 

 section corresponding to the arrangement of the papillae, as mentioned below. 



As Eolis is the type of a family whose anatomy, from its peculiar character, has 

 attracted some degree of attention, we purpose entering rather more into detail than we 

 should otherwise have done : for more complete details, however, we must refer those of our 

 readers who are interested in the subject, to the ' Anatomy of Eolis,' published by one of the 

 authors of this work in conjunction with Dr. Dennis Embleton, in the ' Annals of Natural 

 History,' of which the following is little more than an epitomy. 



The digestive system shows in some parts great divergency from the molluscan type. 

 The mouth opens on the inferior surface of the head, and has large fleshy lips, divided 

 vertically and prolonged into an internal tube, within which is a circular band of strong 

 muscles forming an inner lip, capable of being pushed forwards, and bringing with it the 

 mouth and jaws, when the animal is in the act of seizing its prey. The mouth contains two 

 large horny jaws, placed vertically and nearly co-extensive with the fleshy sides of the 

 buccal mass. They are of an irregularly elliptical or ovate form (PI. 8, figs. 17, 18, 19), a 

 little produced on the upper anterior margin, where they are united by a strong ligament 

 forming a hinge-like joint on which they move : below this two strong arched processes 

 extend downwards in front, forming the cutting edges of the jaw. The tongue is strap-shaped, 

 and covered with numerous transverse plates, armed with spines or teeth directed backwards ; 

 it is attached through its whole length to a wedge-shaped muscular mass, convex above, and 

 extending to the entrance of the oesophagus (PI. 7, figs. 5, 6). The muscular arrangements 

 by which the tongue is moved in different directions, and can be thrown forwards to assist 

 the animal in seizing and securing its prey, are beautifully adapted for the purpose, but it 

 would lead us too much into detail to describe them here.f The lingual teeth differ in 

 different species ; in E. papillosa they are small and very numerous, forming transverse 

 arched rows (fig. 7) ; in E. coronata there is one large central tooth on each plate, with 

 denticulated sides ; and in E. alba a central tooth only, without denticulations (figs. 11, 12). 

 These teeth are very minute. In E. papillosa they are not more than one sixth part the 

 thickness of a human hair ; they are often found broken abruptly off, but never bent ; and, 

 from the circumstance of their resisting all acids but the hydrofluoric, there can be little 

 doubt that they are siliceous. The salivary glands (fig. 6 a) are very small, and placed 

 between the corneous plates and the muscular mass of the cheek. The gland is composed of 



* The capsules in the 4th section have not been examined, but as far as our observations go in 

 the other three this distinction is without exception. 



t See Hancock and Embleton's 'Anatomy of Eolis/ Ann. Nat. Hist, xv, 6. 



