I I 2 



pneumatophore had burst open and the features of the pneumatophore had become irregular, 

 the hypocj'stic villi, moreover, showing themselves outside the outer wall. The unique specimen 

 of this new Pterophysa is exceedingly interesting as far as the structure of its pneumatophore 

 is concerned. On PI. XXII fig. 153 we have represented the specimen as it appears to us, but 

 for the absence of the hypocystic villi. The.se are left out in our drawing as of course in the 

 living specimen these appendages were contained in the interior of the pericystic cavity. Another 

 drawing in black of the pneumatophore (PI. XX, fig. 149) shows the outer wall entirely split 

 open, after we had cut .some small portion of it away, and gives an idea of the beautiful shape 

 of the pneumatocyst, with its silvery wall (secondary ectoderm) and the immense bunch of 

 hypocystic villi of unusual length at its di.stal part. Both the wall of the pneumatosaccus and 

 of the pneumatophore are characterized by their e.Kcessive muscularity, which increases more 

 and more towards the pro.ximal part and reaches its utmost development near the porus. The 

 latter could easily be sounded, the bristle disappearing in the cavity of the pneumatocyst. The 

 ectoderm of the latter is filled with air. We tried to get good sections both of this wall and the 

 outer wall of the pneumatophore. The material, however, seemed to have altered considerably 

 through preservation. But for the chitinous substance and the muscle fibrillae, nothing has 

 remained. No cells, no nuclei were to be found. We do not therefore publish any drawings of 

 these incomplete sections. 



The hypoc}'stic villi are unusually large in Pterophysa (Bathyphysa) Stjideri. When we 

 had cut away distally a small part of the outer wall of the pneumatophore, the remaining 

 Inpocystic villi which were hidden behind this wall all came out and we got the sketch given 

 in PI. XX, fig. 149. We could not distinguish whether there was any regularity in the distribution 

 of these villi on the distal part of the pneumatochone or hypocystic funnel, as H.\eckel calls 

 this part of the pneumatosaccus (88b p. 320). 



Transverse and longitudinal sections through the hypocystic villi are of great interest 

 (PI. XXII, fig. 155, 157, 158, 159). 



After staining some of them we found that in a transverse section the entoderm-layers 

 are numerous, their cells and nuclei are similar to those .sketched on PI. XXII, fig. 156 which 

 was made after material of RJiizophysa Eyseiihardti Ggbr. (Cat. 16) as the entoderm cells of 

 Pterophysa (Bathyphysa) Studeri seem to have altered considerably by ^jreservation (compare 

 transverse section PI. XXII, figg. 157, 158). 



Immediately beneath the numerous entoderm-cells at the top of the villus there lies a 

 nucleus who.se structure is very complicated. Chun 97a tells us that these nuclei usually appear 

 laterally at the distal parts of the cells, sometimes in the middle and rarely at the proximal 

 part. This is the case in Rhizophysa, as sections through hypocystic vilH in Khizophysa Eysen- 

 hardti showed us. In Pterophysa (Bathyphysa) Sttideri, however, they are al\va\s at the proximal 

 club-shaped part in the middle. Moreover we always found only one nucleus in the villi and we 

 wonder whether that im]jlies that there is only one cell, which in that case should have a length 

 of more than 15 mm. (Jn longitudinal sections we found however distinct partitions (PI. XXII, 

 fig. 159); these are very small and thin, but between two cells no nucleus was to be found 

 except the proximal one. (3n the whole there is much unknown in the structure of these nuclei 



