590 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



thalma follow. A. ehhiensis sp. n. has a delicate body, and tlie proboscis is 

 armed with thirty small equal teeth ; it has been observed to reproduce 

 itself either by a single male or female stolon, or by a chain of stolones. 

 A. punctatus sp. n. differs from the last by having a double transverse row 

 of small glands on each segment, and by the armature of its proboscis, 

 which consists of twenty-four unequal teeth irregularly arranged ; A. lugens 

 and A. edwarsi are new species. A. inermis sp. n. is distinguished by the 

 absence of teeth from its proboscis, while A. megodon sp. n. has a small 

 number of well-developed teeth. A few words are said about A. prolifer. 

 Myrianida maculata is fully described. 



When one of the Syllidae projects his proboscis the fleshy papillae 

 which precede it project from the mouth, and serve at first as a tactile 

 organ ; they then enlarge either to embrace a larger space, or to form a 

 sucker, and then the arm which terminates the proboscis is darted rapidly 

 once or twice, as the armed Nemerteans use their stylet. The author has 

 often found adult examples without proboscis, proventriculus, or stomach ; 

 in place of these organs there was a duct like that which is found in sexual 

 stolons, and the moniliform intestine commences at its usual spot. The 

 cause of this irregularity remains for investigation. "When the anterior 

 part of the body is redeveloped the head and the regenerated segments are at 

 first small and of the normal form, but the digestive canal is still a simple 

 duct without proboscis or proventriculus ; this was observed, for example, 

 in Syllis alternosetosa, and Odontosyllis fulgurans. 



In Syllids with direct reproduction the eyes increase very sensibly in 

 size at the time when the sexual elements commence to ripen, and the 

 natatory setae to appear, just as in Nereids when about to take on the 

 epitokous form. It would seem as if in those animals whose existence is 

 specially precious there is a development of the organs which aid them 

 in perceiving and escaping from danger ; of the six eyes the two anterior 

 appear to be rather pigment spots than optic organs. 



A curious change of the muscular system obtains in the regions in which 

 the natatory setae are developed ; the fibres increase in size and appear to 

 become striated ; a similar phenomenon obtains in the region of the 

 remigerous setEe in Heteronereids. The canal of the teeth is very evident 

 in Pionosyllis longocirrata, where it incloses a mass of small glands which 

 are in communication with it and which seem to be poison-glands. Some 

 Syllids have been observed (like a Hesione) to swallow water and even air. 

 In S. alternosetosa it is effected in the following manner ; the proboscis 

 projects beyond the mouth, the proventriculus is distended transversely, and 

 opening half-way along its median longitudinal line there is seen a 

 delicate membrane, formed of circular muscles, which serves as an aspirator 

 by causing a vacuum ; the stomach is distended like the proventriculus, and 

 the air and the water pass directly into the intestine ; the two lateral 

 gastric pouches appear to have the duty of containing the water ; when they 

 are closed their walls are distended and puffed out, and the vibratile cilia of 

 their internal epithelium move very actively. 



Organization of Chlorsemidse. * — M. J. Joyeux-Laffuie finds ten to 

 fifteen specimens of Chlorsema dujardini among the spines of a single ex- 

 ample of the sea-urchin, Toxopneustes lividus. With regard to the numerous 

 club-shaped prolongations, which have been hitherto regarded as parasites, 

 they are probably, as Kolliker has suggested, tactile organs. The two tentacles 

 in the cephalic infundibulum have internally a cavity which is divided 

 into two by a delicate partition ; with this branchiaeform arrangement it is 



* Comptes Eendus, civ. (1887) pp. 1377-9. 



