728 SUMMARY OF CURRENT RESEARCHES RELATING TO 



forms the type of a new family, ChlamydoconclisB, and the author 

 gives it the name of Ghlamydoconcha Orcutti. It is evident already, 

 that the genus does nothing toward bridging the gap between the gas- 

 tropods and pelecypods, but is simply a remarkably aberrant form 

 of the latter group, and probably derived from some form with an 

 external shell. 



Taking-ill of Water in relation to the Vascular System of 

 Molluscs.* — E. Eay Lankester, while recognizing that the supposi- 

 tion that water is admitted by pores into the vascular system of 

 molluscs is supported by the commonly received doctrine that water 

 is admitted by the madreporite to mix with the coelomic fluid of 

 Echinoderms, and that its correlated outpom'ing is favoured by the 

 undoubted fact that the coelomic fluid is occasionally shed through 

 the dermal pores of the earthworm, doubts its occurrence in molluscs 

 in consequence of having ascertained the presence of haemoglobin in 

 the plasma of the blood-fluid of Planorhis, and in the corpuscles of 

 Solen legumen. In Solen no shedding-out of blood-fluid occurs while 

 the surface of the animal is uninjured, and the complete distension of 

 the foot is produced by the simjple mechanism of a rapid flow of 

 blood from the mantle and body into the foot. Planorhis presents 

 evidence of essentially the same kind. 



A distinction must be made between the outpouring of the 

 vascular fluid and the introduction of water through pores on the 

 surface ; on the whole there seems to be no sufficient proof that the 

 pericardium of molluscs is in any case (except that of the 

 Neomeniaj) a blood- space ; and, therefore, the blood cannot escape 

 through it and the renal organs to the exterior. 



The view that water is introduced by pores in the foot is not 

 supported by Lankester's observations on Anodon or Solen, and these 

 pores must be demonstrated, by the supporters of the doctrine, in a 

 way which will satisfy a histologist, and the evidence must not be 

 allowed to rest on experiments made by the diffusion of a soluble 

 colouring matter ; it is to be noted that Griesbach, the present leading 

 supporter of the doctrine, has found that finely divided coloured 

 powder cannot be made to enter the vascular system through the 

 surface of the foot. 



Eyes and other Sense-Organs in the Shells of Chitonidse.t— 



H. N. Moseley, on examining a specimen of SchizocMton incisus 

 dredged in the Sulu Sea, was " astonished to remark on the shells 

 certain minute, highly refracting, rounded bodies arranged in rows 

 symmetrically." On further examination they were found to be eyes, 

 and on search being made in other genera, they were detected in the 

 majority, but in each genus they differ more or less in structure and 

 arrangement. These eyes are entirely restricted to the outer surface 

 of the shells on their exposed areas, and do not extend on to the 

 laminae of insertion ; they are mostly circular in outline, and measure 

 from 1/175 to 1/600 in. They are surrounded and set off by a 

 narrow zone of dark pigment, and in the centre of each convex spot 



* Zool. Anzeig., vii. (1884) pp. 343-6. 



t Ann. and Mag. Nat, Hist., xii. (1884) pp. 141-7. 



