538 ALFRED C. HADDON. 



On Taf. IV, fig. 34, he figures the invagination of the 

 tentacle-sheath, and in the hottom of this depression he shows 

 two large cells. These he imagines form the inner portion of 

 the sheath ; apparently they have the same optical character, 

 as the incipient tentacle-disc, and from what I can make out 

 that organ has not yet appeared. It is strange that the tentacle- 

 sheath should so early differ in optical characters from the 

 remainder of the alimentary tract, when it is derived, by him, 

 from the same tissue, so I am strongly inclined to suspect that 

 this careful observer has fallen into an error, and that the 

 lophophore like the outer portion of the tentacular-sheath, is 

 really an epiblastic derivative, which later on acquires con- 

 tinuity, as far as its cavity is concerned, with the remainder of 

 the digestive apparatus. This correction will give morpho- 

 logical completeness to the whole process. 



Claparede (12) derives the buds from the endocyst both in 

 the larvae and in the adults. In his description of the larva, 

 he says : *' From a certain spot of the endocyst an oval 

 mass projects towards the interior, in which a cavity soon 

 appears. This hollow structure entirely coiTesponds with the 

 invaginated sac of a young Bugula-bud, the development con- 

 tinues henceforth in a perfect parallel with that of the bud. 

 It is very probable that this sac arises from the primitive 

 mouth-furrow of the larva, but I have not directly observed 

 that it does so. I need not describe the formation of the 

 polypide within the sac, as it resembles to a hair that of the 

 polypides of the bud," p. 169. 



From an examination of Smitt's Plates (11), it would seem 

 that the lophophore and oesophagus are at first distinct from 

 the digestive tract in Tubulipora serpens (pi. iv, fig. 9), 

 and in Alcyonidium parasiticum (pi. v, fig. 13-14), and 

 that they subsequently become united. Hincks, who is the 

 English exponent of Smitt, clearly states Smitt's opinion that 

 the buds are derived from the brown-body (•' germ-capsule ") 

 at all events in many cases ; but this view has been so fully 

 discussed and combatted by all subsequent writers, that I need 

 not dwell on it further. 



