REPORT ON THE RADIOLARIA. 23 



which are much heavier than the jelly-body, and produce arm-like protuberances of it ; this modified 

 form, often of very regular and peculiar appearance, I formerly described as Myxdbrachia (compare 

 my Biolog. Studien, loc. cit., and Hertwig, loc. cit., p. 37). 



Dimensions. Diameter of the whole jelly-sphere 5 to 8 mm., of the central capsule 1 to 1'2 mm., 

 of its nucleus 0'3 to 0'4. 



Habitat. Canary Islands, Lanzerote; common, Haeckel; Mediterranean, Messina, Hertwig; 

 surface. 



3. Thalassophysa pelagica, Haeckel. 



Thalassicolla pelagica, Haeckel, 1862, Monogr. d. Radio!., p. 247, Taf. i. 

 Thalassicolla pelagica, R. Hertwig, 1879, Organismus d. Radiol., p. 35, Taf. iii. fig. 4. 



Spherical body in the central part opaque, yellowish, in the periphery semi-transparent, spotted. 

 Central capsule compact, yellowish-white, with a thick and compact membrane, perforated by pores, 

 but not areolated. Diameter of the central capsule about twice that of the nucleus, one-half to one- 

 sixth that of the jelly-envelope. Nucleus papillated, its spherical surface covered with numerous 

 (20 to 60) conical, roundish, or finger-like protuberances, not longer than its radius (commonly only 

 one-half or one-third as long). Enclosed in the semi-fluid substance of the nucleus are very long and 

 thin cylindrical nucleoli snake-like, contorted, and penetrating into the protuberances of the nucleus. 

 Protoplasm of the central capsule in the outer (cortical) zone (on the inside of the membrane) 

 radially striped, with one layer of large oil-globules of different sizes; in the inner (medullary) zone 

 foamy, with numerous small spherical vacuoles, mostly of equal size. Extracapsular jelly-body 

 without dark pigment, contains between its alveoles a large number of large roundish or amoeboid 

 lumps of protoplasm, and very numerous yellow cells or xauthellse (compare the detailed description 

 in my Monograph, and in E. Hertwig's work). 



Dimensions. Diameter of the whole jelly-sphere 1 to 4 mm., of the central capsule 0'5 to 0'6, of 

 the nucleus 0'2 to 0'3. 



Habitat. Mediterranean Messina, Corfu, Nizza, Genoa, Haeckel ; Messina, E. Hertwig ; 

 surface. 



Family II. COLLOZOIDA, Haeckel, 1862 (PL 3). 



Collozoida, Haeekel, 1862, Monogr. d. Radiol., p. 522. 

 Definition. C olloidea socialia. 



The family Collozoida comprises all associated or colony -building Radiolaria without 

 skeleton. We unite here all these skeletonless Radiolarian colonies into one single genus 

 Collozoum, constituted (1862) in my Monograph (p. 522). The oldest known form of 

 it was the Collozoum inerme, described firstly by Johannes Miiller (1856) as Sphcero- 

 zoum inerme. Two other species of the genus were figured (1862) in my Monograph 

 (p. 522, Tafn. xxxii., xxxv.). A most accurate description of its histological structure and 



