34 



The mantle has a balancer on the left side ^), which occurs in all Cavoliniidae. But also 

 on the right side a lobe of nearlv the same size may be seen. 



As to the pallial gland, the jaws, the radula, and the salivary glands, I have nothing 

 to add to what has been published by Souleyet, Boas and Pelseneer. 



I have noticed a gastric coecum, as in all Cavoliniidae; it has not been observed by 

 Pelseneer. For further Information I can refer to this author. Also with regard to the 

 disposition and form of the heart and kidney. 



The gonad occupies the posterior portion of the visceral mass, as in Clio pxraiuidaia. 

 From its dorsal side issues an efferent duet, which exhibits the same elongated swelling as in 

 Clio. I could not clearly perceive a receptaculum seminis at the accessory genital glands 

 (PI. II, fig. 25). Rang already described and hgured ~) (though very inaccurately) a curious 

 appendage, which he took for a gill ; several zoologists after him regarded it as the penis. 

 Most probably it is an accessory copulatory organ, as Souleyet ') and Pelseneer *) suspected. 

 I have also found it in one case (PI. II, fig. 24). The left branch, which terminates in a point, 

 exhibits at its base a thick gland (?), already mentioned by Souleyet. 



The penis is remarkable through the fact, that the horny stylet is slender, and is situated 

 in a pouch at the extremity of the copulatory organ. 



The central nervous system is like that of Clio. Pelseneer °) affirms that the pleural 

 ganglia "are here recognisable externally" ; I owe, that I could not distinguish them clearly 

 from the cerebral or pedal ganglia. The difference betvveen the two halves of the visceral 

 ganglionic mass is more pronounced than in Clio. The second pedal commissure which I have 

 noticed, was sómewhat longer than in Pelseneer's figure "). Two nerves proceed from the 

 anterior part of the cerebral ganglia (PI. II, fig. 26 B). I have seen several nerves issuing 

 from the pedal ganglia and supplying the fins. From the front of the pedal ganglia rises a 

 nerve, which, as we shall see further on, also e.xists in Cymbulia. In this case, in Ciivierina., 

 I have only seen the nerve of the right ganglion, but most probably there is another on the 

 left (PI. II, fig. 26 A, 7). 



The distribution of the pallial and visceral nerves is the same as in Clio., but according 

 to my observations, the origins of the three nerves, issuing from the left ganglionic mass are 

 not so near one another as is shown in Pelseneer's figure °) (PI. II, fig. 26.^^,3,5,6). 



The buccal ganglia form a single mass-, the commissures to the cerebral eanelia, and 

 the nerves issuing irom the approximated ganglia, are the same as in Clio. 



Cavolinia ') Abildgaard. 



1791. Cavolina Abildgaard, Om Cavolina natans, Anomia tridentata Forskalaei, Skriv. Natur- 



hist. Sclsk., Bd. i, Heft II, p. 173. 



1792. Cavolinia Bruguicre, Encyclopedie Methodique; HLstorie naturelle des Vers, vol. I. 



i) Not on the right side, as Pelseneer states, apparently by a slip of the pen (op. s. c, p. i6). 

 2) Hist. nat. des Mollusques Ptéi'opodes, pi. IV, figs. lo — II. 3) Voyage de la Bonite, vol. II, p. 201. 



4J Op. S.C. p. 17. 5) Chall. -Rep. LXVI, p. 17. 6) Op. s. cit., pi. UI, fig. i. 



7) To the list of generic names, given here, must be added, to my opinion : Anomia Forskal (Eaune arabique, p. 124, 1775) 

 and Giocnia Gioëni (Descvizione di una nuova Famiglia e di un nuovo Genere ni Testacei trovati nel littorali di Catania, Napuli, 17S3). 



