ANCESTRULAE OF CAMPTOPLITES 437 



more or less vase-shaped and tapering to a narrow stalk which bifurcates on the sub- 

 stratum to form two main attaching rootlets (Figs. 39 A, B, 40, 41 A, B, 42 A, D). 

 These rootlets may be further branched. The first zooecium springs from the ancestrula 

 near the distal end but is continued down the basal surface of the ancestrula by a struc- 

 ture that I have called the basal band {b.bd. in figures). 



Within this general plan the ancestrulae show differences in the length and shape of 

 both the stalk and the opesia, and in the number of spines, by which seven species 

 appear to be recognizable. Species 1 and 7 (Fig. 39 A, B) resemble each other, and 



' ■ ' ■ ' ■ ' - I 1 ' 



-5 mm 



Fig. 40. Camptoplites. Young colony with ancestrula, species 2, attached to type-material of C. atlanticus. 

 St. WS 773, off Patagonian Shelf. Ancestrula is attached to the frontal surface of the supporting colony, 

 which is stippled, and the roots can be seen passing round the stalk of an avicularium, and under the 

 raised borders of the distal parts of the zooecia. 

 a. ancestrula, av. avicularium, av.s. avicularian stalk, b.bd. basal band, r. tips of two rootlets meeting 



root of ancestrula, r.pl. rosette-plate, 1-3, first three zooecia, seen in basal view, the avicularia and 



opesiae (dotted lines) seen through the zooecia by transparency. 



differ rather markedly from the others in the shape of the ancestrula. Species 2 

 (Fig. 40) has no spines at all, and an ancestrula of rather different shape from any of the 

 others. Species 3-6 (Figs. 41 A, B, 42 A, D) have ancestrulae of similar shape and are 

 chiefly distinguished by the distribution of spines on the ancestrula and succeeding 

 zooecia (see Table 2). A key for the discrimination of the species follows the table. 

 Having thus defined the species it will be possible to discuss their relationship to the 

 adult forms. 



