34 o DISCOVERY REPORTS 



of the zooecium, sometimes with a linear series of smaller similar areas proximal to it 

 (Figs. 14 A-C, 16 B). They can be seen to be the points of attachment of the opercular 

 and parietal muscles, but they are not apparent in young zooecia, presumably owing to 

 the less advanced calcification. They are more conspicuous, when present, in N. tenuis 

 than in the other two species. They have not been seen in N. klugei, but the specimen 

 is not in very satisfactory condition for seeing them. Nor have they been seen in 

 the species of the N. antarcticus group, that part of the wall being covered by the 

 marginal avicularium. They are not peculiar to species of Notoplites. They are present, 

 for example, in Camptoplites areolatus (Kluge) and Amastigia kirkpatricki Harmer, and 

 Busk figured them (1852 b, pi. xxvii, fig. 4) in Tricellaria peachii. 



The ancestrulae are known in only four of the species, two from each group, but it is 

 perhaps worth noticing that the two from the elongatus group are short (slipper-shaped) 

 and give rise to a single zooecium, the branch becoming biserial subsequently, but 

 that in the two from the antarcticus group the ancestrula is tall (vase-shaped) and gives 

 rise to a pair of zooecia (cf. Figs. 13 A, C and 1 1 A, B). On the other hand, ancestrulae 

 resembling those of N. elongatus and N. tenuis are found in species belonging to other 

 genera of the Scrupocellariidae, e.g. in Tricellaria aculeata (see p. 358). 



Key to the species of Notoplites in the collection 



1. Colony biserial ... ... ... ... ... ... ... ... ••• ••• ••• 2 



Colony uniserial 8. N. tenuis var. uniserialis var.n. 



2. Internal spines present, marginal avicularia conspicuous, ectooecium with small uncalcified 



area 1 ... ... ... ... ... ... ... ... ... •■• • •■ • •• 3 



Internal spines absent, marginal avicularia relatively small, or absent, ectooecium largely 



uncalcified ... ... ... ... ... ... ... ... ... ... ••• 6 



3. Frontal avicularium inclined towards neighbouring zooecium 4 



Frontal avicularium inclined away from neighbouring zooecium ... 5 



4. Scutum covering opesia (with rare exceptions), not S-shaped, its proximal lobe broad, 



branches stout 3. N. drygalskii 



Scutum not covering opesia, more or less S-shaped, both lobes narrow, branches slender 



1. N. antarcticus 



5. Distal border of scutum oblique, operculum set obliquely, branches slender 2. N. watersi 

 Distal border of scutum transverse, operculum set transversely, branches stout 4. N. vanhbffeni 



6. Scuta, spines and marginal avicularia absent, joints incomplete or absent ... 9. N. klugei 

 Spines and scuta present on at least some zooecia, marginal avicularia present or absent, 



joints constantly fully developed ... ... ... ... ... ... ... ... 7 



7. Scutum covering opesia, with indented or reduced lumen, basal or marginal avicularia, or 



both, present ... ... ... ... ... ... ... ... ... ... ••• 8 



Scutum not covering opesia, lumen extensive and not indented, basal and marginal avicularia 



absent 7. N. tenuis 



8. Small marginal avicularia present, scutum not thickened, its lumen variously indented, 



cryptocyst smooth, basal avicularia in axil when present, curved ... ... ... 9 



Marginal avicularia absent, scutum thickened and radially striated, its lumen reduced, 



cryptocyst granular, basal avicularia proximal to axil, flat 10. N. crassiscutus 



1 N. perditus, which I have not seen, may come into this group. 



