430 Scientific Intelligence — Zoology. 



of very small dimensions, possess white blood. M. de Quatre- 

 fages presumes that these are the young of P. imbricatus, the blood 

 not acquiring its characteristic tint but by age; and he remarks, 

 that if this conjecture is verified by the observations which he pro- 

 poses to continue, the processes will go on in these molluscs exactly 

 as among the annelides. 



12. On the Development of the Annelides. By M. Sars. — The 

 development of the annelides was only known, till of late years, by 

 works on the leech ; and it Mas erroneously concluded, from ana- 

 logy, that all these animals, on issuing from the egg, had the gene- 

 ral form of body exhibited by the adult. M. Sars has confirmed the 

 discoveries of M. Loven respecting the metamorphoses which certain 

 annelides undergo, by carefully describing the development of the 

 Polinbe cirrata, which is common on the coasts of Norway. 



It is in the months of February and March that reproduction 

 takes place in this annelide. At first the eggs, in the body of the 

 mother, present the usual broken appearance observable in the young, 

 having at one period the aspect of a raspberry, and afterwards be- 

 coming smooth. They are ejected from the body by particular 

 openings in the dorsal surface of the animal, and are then aggluti- 

 nated in a mass by means of viscuous filan>ents, which likewise serve 

 to fix them on the back of the animal, under the branchiae, where 

 they remain till the exclusion of the embryo. When the embryo 

 issues from the egg, its form has no relation to that of the mother ; 

 it is oval, not annulated, and has only two eyes in the anterior part 

 of its body ; the middle of the animal is surrounded with a circular 

 crown of vibratile cilise, which serve for locomotion, and are the only 

 appendages of the body. 



The annelides, we thus see, may undergo important metamor- 

 phoses. They thus approach the other annelides, and also the my- 

 riapodes, embryos of which quit the egg, according to Waga and New- 

 port, in a very imperfect state, and completely destitute of articulated 

 appendages. 



13. On the Development of the Hearing Apparatus in the Mollusea. 

 By Dr H. Frey. — M. Frey's observations have been made chiefly 

 on the embryo of the Lymnia stagnalis. The auditory vesicle or 

 bladder does not begin to appear in this mollusc till the period when 

 the singular rotatory movements of the embryo have ceased, and the 

 animal is now creeping over the interior wall of its shell. We can 

 then notice, without difficulty, at the anterior part of the body, the 

 rudiments of the tentacula, the eyes with their pigment, the tongue 

 with its highly characteristic epithelium. It is on each side of the 

 base of the tongue that the auditory vesicles are found. They are 

 spherical, the contour simple, and the diameter about gV ^^ cV ^^ ^ 

 line (0'038 to 0*04 millimetres). They appear at first to enclose in 

 their interior only a transparent liquid, and are at that time, as is 

 likewise the case with the eye, without connection with the central 



