156 SIDNEY F. HAEMER. 



the effects of the brackish water of the Baltic can be easily ob- 

 served by comparing colonies found in different localities. 

 Those which are nearest to the Baltic are said to have inter- 

 nodes consisting typically of three zooecia; in those most 

 exposed to the North Sea the internodes have seven zooecia ; 

 and in colonies from intermediate localities they have five 

 zooecia. I have not been able to observe any definite correla- 

 tion between the character of the colony and the conditions 

 under which it was growing. 



C. aculeata is less common at Plymouth than either of the 

 preceding species ; it was found on stones^ red seaweeds, and 

 spongesj usually from 4 — 5 fathoms. 



C. cornuta was fairly common, mostly on red seaweeds; 

 while C. denticulata was seldom found at Plymouth. 



By the kindness of Prof, de Lacaze-Duthiers I received a 

 large supply of Crisia from Roscoff in June. The species 

 most common at Eoscoff appear to be C. aculeata, C. denti- 

 culata, and C. cornuta. C. geniculata was less common, 

 and only a few fragments of C. eburnea were found. 



From Mr. J. Sinel I have received numerous specimens of 

 C. denticulata and C. cornuta found at Jersey; and a smaller 

 supply of C. eburnea, C. geniculata, and C. aculeata. The 

 Jersey specimens of C. denticulata were found between tide- 

 marks, while Smitt^ states that C. denticulata is pre-eminently 

 a deep-water form. It is, however, probable that Smitt's speci- 

 mens did not really belong to this species. 



1 have also obtained specimens of several species from 

 Guernsey and the Scilly Islands. 



Smitt's valuable contributions to our knowledge of the Poly- 

 zoa have been devoted, so far as they concern the genus Crisia, 

 to showing that the " species " which have been distinguished 

 in this genus are in reality " forms " of a single species. 



In one of his later papers^ Smitt remarks, speaking of the 

 forms of Crisia discovered in the expedition to which his paper 



' 'Ofvers.,' &c., 1865, No. 2, p. 138. 



2 "Recensio syst Bryozoorum .... Novaja Semlja, &o.," 



•Ofversigt. af-K. Vet.-Akad. Forhandlingar,' 1878, No. 3, p. 12. 



