REPORT ON THE POLYZOA. 33 



The bridge is formed in front of the operculum, starting from each side, with the 

 arches meeting in the middle, thus forming the pore in the peristome. The bridge and 

 pore are formed in this same way in the group, which I maintain should be alone con- 

 sidered as Adeonella, and includes Adeonella ])olyviorpha, Adeonelki j^ictalea, Adeonelln 

 intricaria, Adeonella atlantica, Adeonella j^^^ctinata, Adeonella ^wl ijstomella — all of 

 which I have now seen. In these cases the bridge is formed irrespective of the avicularia, 

 whereas in Gephyrophora p>ohjmorp]ia the arch carries the large lateral avicularia. In 

 Adeonella j>olystomella, Reuss, the arch is not as solid, and the oral sinus can be seen 

 below, but the real structure of the bridge is similar. 



None of this group have the lower margin of the oral aperture straight. This I have 

 alluded to before, but Mr. Hincks [op. cit., p. 152) says that Adeonella intricaria and 

 Adeonella pectinata are described as having the lower margin of the orifice straight ; 

 this, however, only refers to the peristomial orifice. It should be noticed that the figures 

 of the opercula of Adeonella intricaria are given upside down in the Challenger Report, 

 as may be seen from the scale and the mandibles, but when looked at the right way they 

 show that the lower margin is round, Adeonella p>olystornella and Adeonella regulari^ 

 have a distinct oral sinus, but in the other cases the edge is a wide curve. 



It should not be overlooked that the zocecia of this group are all very small, and are 

 about the same size in all the species. 



Adeonella intricaria, Busk (PL II. fig. 39). 



Adeonella intricaria, Busk, ZooL ChalL Exp., part xxx. p. 18-5, woodcuts, figs. 51-53, pi. xxi. fig. 2. 



In the specimen sent to me from Station 190, the young cells have pores .spread 

 generally over the surface in the same way as in Adeonella atlantica, but they are not 

 quite so numerous, and are larger. The small avicularium on the one side of the bridge 

 is very seldom found on the ordinary cells, but usually occurs on the larger or ocecial cells. 

 It is also in these larger cells that the sublabial pore becomes divided by a bar across the 

 pore. As I have already pointed out, the opercula are figured by Busk upside down. 

 The woodcut shows that it has been in part reversed. 



In the mature, but not overgrown, cells the oral aperture can often be seen under the 

 bridge in the same way as in Adeonella polystomella. 



Adeonella atlantica, Busk (PI. II. figs. 20, 37). 



Adeonella atlantica, Busk, Zool. Chall. Exp., part xxx. p. 186, pi. xx, fig. 7; pi. xxi. fig. 1^. 



The pore is placed so low down, that from an external examination it would be 

 supposed that it opened into the zocecial cavity, and several preparations were made 

 (zool. chall. EXP. — PART Lxsix. — 1888.) Kkkk 5 



