8 



over the substratum, and uf stiti", erect and slightly branched tubes, the foreign inclusions of which 

 are more numerous than in the other species. Cavity of erect branches continuous, originating 

 from the irregular cavity of the basal encrustation, into which the zooids can be retracted. 

 Orifices widely infundibuliform, with a tendency to assume an alternate arrangement on two 

 opposite sides of the branch, produced into a few moderately long peristomial filaments. Zooids 

 dimorphic, consisting of neuters and males. 



Neuter i n d i \- i d u a 1 s with an elongated metasome, the stalk originating nearly from its 

 aboral end; gonads absent, or represented by mere vestiges, or perhaps occasionally developed 

 into functional testes. Tentaculiferous arms four pairs, apparently without end-bulbs and vesicles. 

 All parts of the epidermis are densely pigmented. 



Male individuals with conical body, which passes continuously into the stalk; 

 alimentary canal vestigial; testes two, occupying most of the metasome and part of the stalk, 

 and opening in the same position as the ovaries in the other species. Arms reduced to a single 

 pair, without tentacles, their epidermis being crowded with large, highly refracting vesicles. 

 Epidermis highly pigmented. 



In both kinds of individuals the stalk is e.xcessively long and slender, and apparently 

 produces buds in great profusion. 



IV. COEXOECIUM. 



It has been pointed out above that excellent specific characters are afforded by the 

 coenoecium, which, however, has a well marked generic character. It is in all cases provided 

 with a number of definite orifices, which in the species investigated, are usually bordered by 

 one or more peristomial processes; and it is entirely composed of a series of superposed lamellae 

 of more or less pronounced orange colour and of gelatinous consistency, as described by 

 M'Intosii (87, p. 5) in the type-species. Many of the lamellae include various foreign bodies, 

 such as Foraminifera, Sponge-spicules, particles of mud and so on, to an extent varying with 

 the species. These lamellae closely resemble tlie rings which compose the tubes of Rhabdopleiira. 

 A careful examination of the free portions (^peristomes") of the tubes in that genus (PI. II, 

 fig. 19) shews that the rings are not unbroken, but that each is interrupted by an oblique 

 suture. The suture is easily seen when it is on that side of the ring which faces the observer (a), 

 less easil)- when it is necessary to focus through the tube in order to see it (<$), and may be 

 difficult to distinguish when it lies on either edge of the tube [c). I believe, however, that the 

 .suture is a typical feature of the tube-ring; and that it indicates that the zooid, in constructing 

 a new ring, begins at a definite jioinl and works round the entire peripherj' of the tube until 

 it returns to its starting pcjint. It may be presumed thai tlie pari of the new ring £rst secreted 

 has by this time somewhat hardened, so thai the junction of llie first- and last-formed part of 

 the tube is indicated by the suture. This point escaped the notice of S.\rs (72, p. 3), who 

 .supposed the rings of the peristome to be uninterrupted, while he figures the sutures (PI. I, 



