part 3] THE KELESTOMINJE. 219 



avicularia accompanying each normal cecium, and a less specialized 

 (though extraordinarily complex) secondary aperture; and Jl. j/'kes- 

 hrownei, with a pair of avicularia to each normal cecium, and a 

 secondary aperture formed of structures so specialized that, were it 

 not for comparison with Kelestoma and JMCorphasmopora hrydonei, 

 they would be almost impossible to interpret. The ancestrceeium 

 of 31. hrydonei shows characters that fall into three categories : 

 namely, primitive, youthful, and special. 



All the material described is from the Senonian, zone of 

 Belemnitella mucrbnata, of Riigen, except ametatype specimen of 

 JMbrjokasmopora jukes -brownei. from the same zone at Trimiugham, 

 Norfolk, in the British Museum Collection (D8005). 



Discussion. 



Dr. S. F. Haemee did not feel able to estimate the value of the 

 Author's results, as these are at present represented only by pre- 

 liminary accounts. He believed, however, that the Author is 

 engaged on a very valuable line of investigation, and that the 

 gratitude of zoologists is due to him for his efforts to trace 

 the , lines of evolution of the forms to which he is devoting his 

 attention. 



The study of Recent Cheilostomata is full of difficulties, and the 

 Author's work should help to remove some of them. The family 

 Cribrilinidse, as represented in the recent fauna, corresponds in the 

 main with the Author's ' Cribrimorph Polyzoa.' It is, perhaps, 

 doubtful whether the large number of families and subfamilies 

 recognized by the Author are really required ; and a question was 

 asked with regard to the effect of these subdivisions on the arrange- 

 ment of the Recent forms. It might be anticipated that the 

 divergence which already existed in Cretaceous times would have 

 continued to take place, in which case it might prove necessary to 

 place most of the genera, and even many of the species, of existing 



* Cribrilinidse ' in separate families. The hope was expressed that 

 the Author would define his position with regard to this question. 



The necessity for the introduction of certain terms used 

 by the Author was questioned ; and the word ' cecium ' was 

 especially mentioned. The Author had informed him that this 

 term had been introduced in place of 'zocecium' for fossil skeletons, 

 on the ground that ' zocecium ' implies the presence of soft parts 

 and because ' cecium ' is convenient in forming compound words. 

 No objection was made to the use of ' cecium ' in compounds, but 

 it was contended that it is not required on other grounds. In its 

 modern sense the term ' zocecium ' was introduced by Smitt (as 



* zoocecium ') in 1865, although a variant ('Zocecies') had been 

 employed by Lamouroux, in a somewhat different sense, as early as 

 1816. In both cases the idea underlying the use of the term was 

 that the zocecium is the house of the polype or polypide ; and 

 although it is now recognized that it is merely the body-wall, 

 frequently calcified, of an individual of the colony, its use is 



