I I 



and their surrounding villi and as we intended to keep the material of the Siboga as complete 

 as possible, we could not permit ourselves to cut up the entire pneumatophore of Pterophysa 

 (Bathyphysa) Stiideri, as we could not be certain owing to the incompleteness of preservation 

 in the proximal part of the pneumatophore, that this would be better in the distal part. 



The first figure (PI. XXII, fig. 157) shows a very complicated structure, the nucleus 

 being branched and divided in all directions, the second (PI. XXII, fig. 158) shows an increase 

 in size of the whole and less irregularity. On the left side the branches seem to approach the 

 entoderm-cells whilst in the upper part of the drawing to the right, the smooth wall of the nucleus 

 is situated at a greater distance from the entodermal layer. In both drawings the entoderm-cells 

 are irregularly shaped, owing to considerable alteration by the preservative fluids. 



The distance between the proximal part of the cell with its huge nucleus and its distal 

 wall is enormous. The distance between the next transverse wall and its proximal one is less, 

 but in this smaller cell we never found a nucleus nor in the distal part of the hypocystic villus. 

 The villus is never branched as is the case in Rhizophysa Eysenhardti. This we could not 

 ascertain in the distal part (where the villus is attached to the base of the air-funnel). 



The transverse sections of a nucleus and its surrounding entoderm-cells are taken in the 

 direction marked by the lines (PI. XXII, fig. 155. "fig. 156" "fig. 157") on the longitudinal section. 



The drawing of the whole specimen of Pterophysa (Bathyphysa) St7ideri (PI. XXII, 

 fig. 153) does not show any young buds of appendages. These are, however, present, but are 

 situated on the other side, as can also be seen from the situation of the first mature siphon. 

 They are situated on the strongly muscular stem in a deep gTOOve, which one can follow all 

 along the stem. The latter has a length of about 70 cm. and appears to us as if it were strongly 

 contracted. It resembles absolutely (and this is of great importance) the stem of Bathyphysa 

 abyssoritni as Studer 78 describes it, parts of which were drawn again for us from the original 

 material, thanks to Prof. F. E. Schulze's kind assistance. The same flatness which makes it 

 similar to a strong ribbon and the same groove were noticed by us. 



The successive stages of development of the siphons are quite different from those in 

 Pterophysa grandis. There appears, very much sooner, — only 28 mm. beneath the very first 

 indication of a future siphon — a probably full-grown siphon, having a length of 26 mm. There 

 is a small pedicle at the base of the siphon (PI. XXII, fig. 154); this is one of the reasons 

 combined with the extreme toughness of .stem and pneumatophore, the size of the latter and 

 the shape of the stem, why we incline to consider our specimen very closely related to Studer's 

 Bathyphysa. Of course points of absolute resemblance there are none, but any one who compares 

 the sketches in Studer's work with our Pterophysa grandis (Cat. 8) must acknowledge that 

 Cat. 6 shows a much closer similarity to Studer's than to Fewkes' specimens. To call our 

 specimen BathvpJiysa we thought too daring; we therefore used the specific denomination Stiideri 

 to show the evident relation there exists between this Siboga-specimen and Studer's material. 



The shape of the siphon is elongate, its central cavity shows already a definite development 

 of entoderm-cells and though we could not sound the aperture, there is every reason to believe 

 that the siphon will soon break open and begin its functions. The ptera are opaque, tough 

 structures (see transverse section PI. XXIII, fig. 165); they seem to be very strong and differ 



S1B0G.\-EXPEDITIE IX. 1$ 



