ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 533 



rapid. In the females similar genital openings are present, but the ova 

 escape much more slowly than the sperms. In aquaria the discharge of 

 sperms by a male appears to stimulate all surrounding ripe animals, 

 and they similarly discharge their products. The development of the 

 eggs was watched, and the identity of the young with the Mitraria of 

 Metschnikoft' established. 



Respiration in Spirographis spallanzanii.* — M. Bounhiol noticed 

 that when the water in the aquarium was not changed this Annelid 

 left its tube in 10-12 hours, as if to accelerate tbe cutaneous respiration. 

 This led him to a series of experimental studies on the respiratory 

 activity. The co-efficient of respiratory activity varies considerably 

 according to the conditions ; the animal shows a remarkable plasticity. 

 Small specimens breathe for equal weights much more actively than 

 large ones, the surface being relatively greater in the former. After 

 loss of the gill, there is a rapid compensation by increase of the 

 cutaneous respiration. The cutaneous method is much the more im- 

 portant, effecting at least three-quarters of the total respiration. 



Structure of Saccocirrus.f — E. S. Goodrich has studied this worm 

 (S. papillocercus) at Naples, and has been able to amplify and correct 

 previous observations. He finds that the last 10-12 segments have 

 neither parapodia nor cluette ; there is a stomatogastric nervous system ; 

 in the male genital region the nephridia open into the coelom, and also 

 into the ducts of the sperm-sacs, while in the female the corresponding 

 nephridium opens by a minute pore into the base of the spermathecal 

 duct. As in Protodrilus, there is a special head-cavity, which is pro- 

 bably the coalom of the first segment. In a discussion on the systematic 

 position, the author emphasises the affinities with Polygordius and Proto- 

 drilus, and maintains that the so-called primitive characters of the two 

 latter (absence of parapodia and chaetae, &c), are really the result of 

 specialisation. He suggests the suppression of the group Archiannelida, 

 and the inclusion of the three genera in Lankester's group Haplodrili, 

 as specialised offshoots of the Annelid stem, and not as ancestral forms. 



Structure and Affinities of Echiurus unicinctus. J — Miss A. L. 

 Enibleton has obtained numerous specimens of this Japanese Echiuroid 

 from Tokyo, and has for the first time subjected it to a thorough ex- 

 amination. She finds that it differs so much from the British E. pollasii 

 as to suggest the necessity for the formation of a new genus. There is 

 no extensible proboscis, this beiug represented merely by a short blunt 

 prostomial lobe. There is no trace of a closed vascular system, hitherto 

 believed to be characteristic of Echiuroids. There is a definitely 

 marked band of compound glands in the skin, and a single circlet of 

 perianal hooks. The inner funnels of the segmental organs are pro- 

 duced into long tapering arms which are spirally grooved and densely 

 ciliated. The mesentery or diaphragm, present alike in E. pallasii and 

 in Tlialassema neptuni, are here absent, and the alimentary canal does 

 not appear to be divided into regions. On the other hand, except for 

 the perianal bristles in E. pallasii, that species resembles Tlialassema 



* Comptes Rendus, cxxxii. (1901) pp. 1348-51. 



t Quart. Journ. Micr. Sci., xliv. (1901) pp. 413-28 (3 pis.). 



% Trace. Linn. Soc. (Zool.), viii. (1900) pp. 77-97 (4 pis.). 



Oct. 16th, 1901 2 o 



