Prof. A. Dendy. On a Pair of Ciliated Grooves 



one of these was briefly described by Kner in 1869*; the other was 

 for many years in the Museum of the Otago University, Dunedin, 

 and was forwarded to me for investigation by the present curator, 

 Professor W. B. Benham, D.Sc., to whom I desire to express my 

 indebtedness for his great kindness. 



The specimen which I have thus had the opportunity of investigat- 

 ing Avas labelled in the handwriting of the late Professor T. J. Parker, 

 F.R.S. "Ammoccetes stage of Geotria Opoho Creek. Jany., '84. 

 Chromic and Osmic." It; had evidently been preserved with the 

 utmost care, and proved, in spite of its age, to be in an admirable state 

 for histological investigation. 



The total length of the specimen was about 57 mm., and the 

 greatest diameter in the middle 3'5 mm. With a view especially to 

 the study of the parietal organs, the head region was cut into a 

 series of transverse sections b}^ the usual paraffin method, and the 

 sections were stained on the slide ; for staining, carbol-fuchsin proved 

 satisfactory. 



On examination, the sections thus prepared showed not only a 

 well-developed parietal eye and the structures usually associated there- 

 with, but also a pair of conspicuous ciliated grooves lying in the roof 

 of the brain in the neighbourhood of the posterior commissure. These 

 grooves run longitudinally from the recessus sub-pinealis to the 

 hinder margin of the posterior commissure. They are most conspicuous 

 beneath the commissure itself (figs. 1, 2), in which region they are 



FIG. 1. 



.Ch.Pl 



Com. P., 



-M.C. 



Tr. 



Tr 



* " Keise der Oslerreichischen Fregatte Novara um die Erde,"' Zoologie,' 13J. 1, 

 Fiscbe, p. 421 . 



