Literary Notices. xlvii 



their being long overlooked. The curious segmental sensory patches 

 which were described by the author as accessory optic vesicles arise in 

 in a way similar to that of the eyes. They first make their appearance 

 when the neural plate is broadly expanded. Four pairs of such organs, 

 at least, are noted, the cephalic pair forming, as is claimed, the pineal 

 body. They are embryonic and transitory structures and are thought 

 to point back to a multiple-eyed pre-vertebrate condition. 



A review of the literature upon the pineal seems to the author to 

 lend force to the suggestion of a multiple-eyed ancestor of vertebrates. 

 The results '' go to show that there are two distinct outgrowths of the 

 thalamencephalon of Petromyzon, Teleosts and Lacertilia." The ceph- 

 alic one is that developed into the pineal eye in front of the epiphysis 

 in Lacertilia, and corresponds to Hill's anterior vesicle in teleosts. 



In passing, it seems that a halt ought to be called in the unjusti- 

 fiable introduction of untranslated descriptive terms from the German. 

 " Zirbelpolster " is not an English word and is not a desirable addition. 

 If a popular term is needed it may be easily translated but it is much 

 better to substitute a Latin ecjuivalent. Our European friends should 

 also realize that the scientific world cannot consider an organ properly 

 named and presented for acceptance until a name has been proposed 

 conformable to the common nomenclature of the scientific world. 



The auditory organ is briefly discussed and its relation to the lat- 

 eral line system recognized. 



The paper supplies many details that have been wanting hitherto 

 and has several pregnant suggestions, but its chief value is in the com- 

 pleteness and apparent accuracy of illustration. 



c. L. H. 



The Sensory Physiology of Actiniaiis.^ 



Recognizing the growing importance of the comparative physiolo- 

 gy of the nervous system, especially among the lower invertebrates. 

 Dr. Parker has undertaken a series of experiments on the common ac- 

 tinian of the Atlantic coast, Metridium marginaium. In taking food, 

 two kinds of responses are met, ciliary and muscular ; only the latter 

 shows evidence of nervous control. Numerous experiments illustrate 

 the slight physiological centralization in the nervous functions of these 

 organisms. Each tentacle acts like an independent organism. The 

 curious fact is observed that the cilia on the lips reverse their motion 



^Parker, G. H, The Reactions of Metridium to Food and other Sub- 

 stances. Bui. Museum Comp. Zool., XXIX, 2, March, 1896. 



