ZOOLOGY AND BOTANY, MICKOSCOPY, ETC, 655 



eyes, but yet that sucli impressions differ in a manner of wliicli we 

 have no conception. This, however, seems improbable, and on the 

 whole therefore it certainly does appear that Daphnias can distinguish 

 not only different degrees of brightness but also differences of colour. 



Vermes. 



Anatomy and Histology of Polyophthalmus pictus.* — E. Meyer 

 gives a detailed account of the structure of this Polychtetous Annelid. 

 The nervous system is described as consisting of (1) a cerebrum made 

 up of several pairs of ganglia, and appearing externally not to be 

 composed of two lateral symmetrical lobes, but as compact and smooth ; 

 (2) of two long oesophageal commissures, and (3) of a ventral cord 

 which presents distinct swellings in its anterior portion only. In 

 dealing with the sensory apparatus, attention is directed to the ciliated 

 organs which lie just behind the cephalic lobes. These do not appear 

 to be, as Quatrefages has thought, organs comparable to the " wheels " 

 of the Rotatoria, but rather as something analogous to the olfactory 

 organs of higher forms. The species in question has twelve pairs of 

 lateral eyes, which seem to have the same typical structure as the eyes 

 of other Annelids. 



The body-cavity is divided into three chambers ; the largest of 

 these is perivisceral, and contains the digestive tract ; the other two 

 are smaller, and are placed at the sides. There is not, for the greater 

 part of the coelom, any metameric cameration ; some of the segmental 

 organs appear to function as efferent ducts for the generative products. 



Annelids from Thau.f — H. A. Eobin gives some account of Piono- 

 syllis jJulUgera and Gruhea limhata ; with regard to the former, he 

 points out that Claparede had noted the presence, in those segments 

 of the adult male that lie in front of the testicular segments, of a 

 number of c^ecal tubes, which seemed to be segmental organs in a 

 greatly modified condition, and possibly of testicular function. The 

 author has been able to convince himself that the structures in ques- 

 tion are pedal glands, and that they cannot be considered as testicular, 

 inasmuch as they are often found in the same segment as a well- 

 developed testicle. In both the species examined the young appear 

 under the chaetopodous form, and do not pass through a larval stage ; 

 on escaping from the egg, the yoimg has a well-developed head, 

 although this is not distinct from the buccal segment ; there then 

 succeeds an apodal, then three setigerous segments with feet, and then 

 an anal joint. The head is provided with antenna and eyes, but has 

 no pigment-spots ; behind the eyes the young may be seen to be pro- 

 vided with ciliated pits analogous to those found in the Nemertiuea, 

 but they do not seem, as is the case with G. fusifera, to be carried on 

 into the adult stage. 



Observations on Phreoryctes and Nais.J — R- Timm finds that the 

 cuticle of Phreoryctes is not only much better developed, but that its 



* Arch. f. Mikr. Anat., xxi. (1882) pp. 769-823 (2 pis.), 

 t Bull. Soc. Philom. Paris, 23rd December, 1882, 7 pp. 

 X Albeit. Zool.-Zoot. Inst. Wiirzb., vi. (1883) pp. 109-57 (2 pis.). 



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