BRYOZOA O^ THE PHILIPPINE REGION 551 



center, at the bottom of which are large and scattered vacuoles. 

 (Fig. 2.) 



The pinnules are unequally developed and bear 3 to 6 peristomes. 

 Generally there are only two series of tubes between the pinnules 

 but on certain branches and without apparent reason the distance 

 becomes much greater and there may be 10 series of tubes between 

 two successive pinnules. 



The peristomes of the same transverse series are never adjacent 

 save at the extremity of certain branches when they are not entirely 

 developed. The peristomes are all equally salient; the lateral peri- 

 stomes are no longer than the others. 



The general aspect of the dorsal is rather constant. The nervules 

 separating the sulci are little salient and their number depends 

 evidently on the size of the branches. On the terminal branches of 

 the large colonies the nervules are more apparent, more salient, 

 smooth, and their ovicells bear a large longitudinal keel. Harmer, 

 1915, discovered an analogous arrangement on Eornera spinigera 

 Kirkpatrick, 1888. (Figs. 3, 4.) 



The ovicells are arranged obliquely and laterally on the dorsal. 

 They are supported on a pinnule and their oeciostome opens on the 

 cellullar face between the pinnule and the colony. The pores are 

 generally larger than the vacuoles. Their dimensions are quite 

 variable although rather constant on the ovicell itself. The dimen- 

 sions and the form of the ovicell are so variable that no two are alike. 



The very irregular arrangement of the branches does not permit 

 the preparation of good longitudinal sections but those that we have 

 made revealed the ordinary structure of Hornera. The entire colony 

 is surrounded by a very thick epitheca traversed by the thin and 

 recurved vacuolar tubes. 



Affinities. — This species differs from Eornera spinigera Kirk- 

 patrick, 1888, in the equality of the peristomes (the lateral peri- 

 stomes not being longer), in the absence of long peristomial spines, 

 in the regular arrangement of the alternate series and in the presence 

 of shorter pinnules. 



Biology. — This species lived in the localities richest in bryozoa. 

 It is entirely equatorial and does not pass beyond the 10th parallel. 

 It occurs in the China Sea and we have found it on the west coast 

 of Borneo. Its bathymetric range (32-388 meters) is rather great, 

 but it is between 40 and 97 meters that it is best developed. 



The number of larvae emitted by a single ovicell in the cyclo- 

 stomata is considerable, but the larva of Hornera swims about but 

 a short time. It affixes itself rapidly and in this species as in other 

 orders it is not rare to find numerous colonies with their base on a 

 very small surface. These colonies attain large dimensions only 

 rarely. Their life must then be very precarious but we have not 

 yet discovered the causes of the sudden arrest in their development. 



