WOODWARD : ANATOMY OF VOLUTA, ETC. 1 1 9 



i front of the nerve-collar. The latter pair consists of large, compact, 

 . but acinous glands, situated on either side of the oesophagus near 

 the base of the introvert, and communicating with the alimentary 

 canal by a pair of fine ducts, which run parallel to the oesophagus 

 under cover of the thick circular muscle and eventually open into the 

 buccal mass close to the oesophageal aperture. The tubular glands, 

 which are perfectly distinct from these, consist of a pair of slightly 

 coiled muscular tubes, largest at the blind posterior extremities and 

 tapering off in front ; they lie below the racemose glands, and their 

 free ends pi'oject outbej T ond these structures ; hence Bouvier, following 

 Quoy & Gaimard, mistook them for tubular backward prolongations 

 i of the racemose glands. The tubular glands meet in the middle line 

 , below the radula-sac, and thence run forward as an extremely fine 

 I duct closely bound up with the latter structure, into which the duct 

 opens in front of the odontophore (Fig. 6). The oesophageal caecum 

 ('Anhang an der Speiserohre' of Kieferstein ; the great fore-gut gland of 

 Haller) is one of the most striking features in the anatomy of Yoluta 

 and its allies. A blind outgrowth of the oesophagus appears to be 

 present in the majority of the Khachiglossa behind the nerve-ring, 

 but it nowhere attains such a striking development as it does in the 

 Volutidae. In Yohda this organ has the form of a long coiled 

 muscular tube, of considerably larger size than the oesophagus, into 

 which it opens ventrally just behind the nerve -collar. In the 

 undisturbed condition this organ is found lying coiled up on the top 

 of the oesophagus (Fig. 1, o.c.) and presenting a shiny white appearance. 

 Even in quite a small Volute the ca3curn, when uncoiled, measured 

 nearly 8 inches in length. 



The radula of this form calls for no comment, since it is typically 

 volutoid, consisting of a stout ribbon bearing about 43 large tricuspid 

 teeth, each tooth constituting a transverse row. 



The nervous system. — Very little is known of the nervous system of 

 a typical Volute, for Quoy & Gaimard's figures show nothing beyond 

 a nerve-ring, and Bouvier' s description and figures, though giving 

 great detail, refer, as already noted, to the genus Melo, in which 

 the nervous system differs somewhat from that of Yoluta an cilia. 

 An examination of Fig. 9 will give a fair idea of the nervous 

 system of this Volute, and it will be at once evident that it is 

 characterized by extreme concentration round the oesophagus. The 

 two cerebral ganglia are closely connected in the middle line, and 

 are still more intimately fused to the pleural ganglia behind and 

 below. The cerebro-pedal and pleuro-pedal connectives are so short 

 and broad that it becomes almost a difficult matter to distinguish 

 between the pedal ganglia on the one hand and the cerebrals and 

 pleurals on the other. The cerebral ganglia give off about four 

 conspicuous nerves, which run forward to the head-lobes, tentacles, 

 and eyes, and also a pair of small nerves which run inward to the 

 buccal ganglia (b.g.), the lattei', as in other Rhachiglossa, being 

 situated close to the nerve-collar. The pedal ganglia are somewhat 

 abruptly truncated ventrally, and give off numerous nerves to the 

 large foot. From the right pleural ganglion arises an extremely short 



VOL. IV. — OCTOBER, 1900. 9 



