^fisreU^Aneous. 281 



The posterior brain, which, in tliis form, is distinctly dorsal, is 

 very strongly developed ; it gives otF two large nerves which pass 

 into the caruncle. The latter organ, which was misinterpreted by 

 Ehlers (18G4), has recently been described by Mcintosh (1894), 

 who, however, did not recognize its true nature and saw in it 

 nothing but some fibres. Its innervation, however, shows that the 

 caruncle is nothing else than the nuclial organ. It is formed, in 

 fact, by three elongated folds of the body-wall. One of these folds 

 is of greater length, and is placed between the other two ; its lower 

 edges are united to the inner edges of the lateral folds. Vibratile 

 furrows, which are very distinct and parallel, run the entire length 

 of the folds. There are four of them on the median fold, and only 

 two on the lateral ones. Two of the vibratile furrows pass 

 from the caruncle on to the cephalic lobe, and extend as far as the 

 paired antenna?. 1 shall describe this arrangement in detail else- 

 where. I am likewise unable to dwell here upon the histological 

 structure of the caruncle, which, moreover, does not differ essentially 

 from that of the same organs in other Polychsetes. The three folds 

 indicated above are entirely similar to the occipital lappets (ailerons 

 occipitaux) of e. g. ^H?6///o*(7/is. Their union into a single mass 

 only disguises the primitive condition which is still represented in 

 Etrphrosiiie triJoha, Ehlers. 



The glandular organs which, according to Mcintosh (1894), are 

 found on each side of the caruncle, are nothing but masses of pigment 

 deposited in the posterior lobes of the brain. Similar masses are 

 also found along the pedal nerves, and also in other Polychaetes (e. g. 

 ventral chain of Eunice). Veritable glandular organs, however, 

 exist. These are two pyriform masses, constituted by greatly 

 elongated hypodermic gland-cells. These organs belong to the palpi ; 

 for if the bodies of the cells are situated behind the brain, their 

 ducts open on the surface of the palpi. 



In the genus Sjnnther the tend(?ncies indicated at the commence- 

 ment of this note have been realized much more completely. The 

 parapndia of the first segment have become united in front of the 

 cephalic lobe. The caruncle has disappeared equally with the palpi 

 and the paired antennte. The unpaired antenna of the Amphino- 

 mida3 alone persists, with its four eyes at its base. 



The presence of four of these organs upon the dorsal face and at 

 the base of the unpaired antenna clearly indicates that Sjnnther 

 cannot be the direct descendant of Euplu-osine. These two genera 

 form two distinct branches from the stem of the Amphinomidoe. 

 The tendency towards radial symmetry which is displayed in Spinther 

 as in Euphrosine must not be attributed to a direct parental con- 

 nexion between the two forms. The explanation of the phenomenon 

 is to be sought in a convergent evolution occasioned by a mode of 

 life almost as sedentary as that of fixed animals. — Comptes Rendus, 

 t. cxix. no. 26 (December 24, 1894), pp. 1226-1228. 



On the Development of the Kidneji and of the Ccdome in Cirripedes. 

 By A. Gruvel. 



In the paper which I have published in the ' Archives de Zoologie 



