REPORT ON THE ACTINIARIA. 127 



specimens having been badly preserved. As both the ectodermal epithelium and muscles 

 were almost entirely macerated away, so also all the endodermal parts formed a disinte- 

 grated mass in the radial chambers. The muscles of the septa were nowhere preserved, so 

 that I could only form an idea of their course from the furrows on the surface of the 

 supporting lamellse. These were, however, not very distinct, as the muscles of the septa, 

 like the muscles of all the other organs, are extremely weakly developed ; as far as I 

 could make out each septum bears longitudinal muscles on the one side, and transverse 

 muscles on the other, as in other Actinise. 



All the septa are furnished in the section below the oesophagus with reproductive 

 organs which reach like long, broad, folded bands almost as far as the pedal disk, but the 

 mesenteric filaments were macerated away and nowhere to be found. 



Besides the twenty-eight perfect septa there are imperfect septa, which only reach as 

 far as the middle of the oral disk, and do not bear reproductive organs. I did not 

 determine the number of them by direct observation, as in order to do this I should have 

 been obliged to dissect the entire animal, and I could not make up my mind to this, 

 considering how insufficiently it was preserved. I estimate them at twenty-six, as in tiie 

 majority of Actiniaria the aggregate number of the tentacles nearly corresponds to that 

 of the septa. 



Though the anatomical description here given is but deficient, I consider myself justi- 

 fied in regarding Porponia elongata as a form systematically interesting. The position 

 of the tentacles in a double row, the presence of perfect reproductive septa (macrosepta) 

 and imperfect sterile septa (microsepta) are characteristics which recall the Zoanthese ; the 

 numbers of the tentacles and the septa likewise agree with those of this group, as they are 

 neither multiples of the number six, as in the Hexactini^e, nor of the number four, as in 

 the Paractinise. On the other hand, having two oesophageal grooves, Porponia elongata 

 comes closer to the Hexactinise, among M'hich, as I have already specially observed (p. 30), 

 it most resembles the Antheomorphidse. I therefore consider it most likely that Porponia 

 elongata is an intermediate form between the Hexactinise and the Zoantheae. 



Porponia rohiista (PI. I. fig. 10). 



Body compressed, as high as broad, sessile ; wall tough, the upper end prolonged into 

 numerous scimitar- shaped processes, which support the outer walls of the long, thin- 

 walled saccular tentacles. 



Habitat.— Station 237. June 17, 1875. Lat. 34° 37' N., long. 140° 32' E. Depth, 

 1875 fathoms. One specimen. 



Dimensions. — Height, 4 cm. ; breadth of the oral disk, 4 cm. ; breadth of the pedal 

 disk, 3 cm. 



The single specimen of Poi-ponia robusta had unfortunately been preserved in 

 chromic acid, and had therefore become so brittle that I must confine myself to a 

 description of the external form of the body. The animal is shaped like a short. 



