58 The Ottawa Naturalist. 



interesting form for the study of mural pores and their relations. The 

 affinities of this genus are likewise discussed and seem to point to 

 Aulopora and Romingeria rather than any other genera of the per- 

 forata excepting Michelinia and Pleurodictyum. The first stage of 

 Pleurodictyum and of Favosites is an auloporoid stage represented 

 by the initial cell. 



Geology of Aylmer Onthe 27th of March, 1895, oneof our mem- 

 bers, Mr. T. W. E. Sowter, delivered a lecture on the "Palaeontology 

 and Geology of Aylmer at the Academy. The lecture proved to be 

 very interesting and was illustrated by a large suite of specimens con- 

 sisting of rocks and fossils, some new to science. We are pleased to 

 state that we expect to receive a paper from Mr. Sowter on the above 

 subject for the pages of the Naturalist in the near future. 



Zoology Tunicata of the Pacific Coast of North America. 



1. Perophora annectens, n. sp. By William E. RiTTER. Proc. Cal. Acad. 

 Sc, Vol. IV, Part I, pp. 36-S5, Plates I. II. and III., ngs. 1-39. Sept., 

 1894. 



This is an interesting and exhaustive biological study of one of 

 those interesting species of tunicates which abound along the rocky 

 coasts and shores of the North American Pacific. The species here 

 described for the first time is from Monterey Bay, California. The 

 author gives first a general summary of our knowledge of simple and 

 compound ascidians, and points out that with the result of his researches, 

 the importance of this old classification becomes " nil" 



Perophora Hutchinsoni, from Australia, and P. viridis from the New 

 England coast of North America are the latest forms brought under 

 Wiegmann's genus established in 1835. Then follows a diagnosis of 

 the species with a general description dealing with the mode of occur- 

 rence of the ascidiczooids in their colonies. Their histological charac- 

 ters are very ably described. This form is a particularly favorable one 

 to study owing to its wonderful transparency. The test and the origin 

 of its cells receives special attention. The results of Ritter's work con- 

 firm those of Salensky and Kowalevsky on the same subject, showing 

 that the cells of the tunicate test are not derived from the ectoderm 

 but from the mesoderm. Dr. Ritter says : " I believe this to be due to 

 the fact that the cellulose substance of the test is here being formed. . 

 I have no evidence that the matrix or cellulose portion of the test is 

 produced as a secretion of the mesodermal cells imbedded in it 







