,'iO.'2 VRITZ .MULLEUj ON THE 



exceed this. The relative age of the branches is usually 

 clearly manifested in their coniparatiAC thickness and length, 

 as well as in the amount of their subsequent brancliing. 



The joints themselves are soft and flexible, but at the same 

 time elastic, not unlike, in this respect, portions of intes- 

 tine distended Avitli water and tied at each end. The delicate 

 but strong walls, which, from their insolubility in boiling caustic 

 potass, are probably composed of a chitinous material, are, as 

 well as tlic contents, nearly as clear as water. A slight 

 degree of yellowish opacity is caused by the presence of a 

 pigment with which the imicr' surface of the membrane is 

 coated. The youngest branches appear the least transparent, 

 whilst in the older ones the view is often intercepted by 

 animal and vegetable parasitic growths of various kinds. 



From observations on other Ctenostomatous Polyzoa, I am 

 induced to think that the individual joints or internodes are 

 >;eparated by transverse dissepiments. 



The polyzoary adheres to fuci, &c. by means of much- 

 branched radical filaments, which arise sometimes at the 

 extremity of a brancli in place of a twig (fig. .2 a), some- 

 times at indeterminate points of the stem, especially between 

 the cells (fig. 3 6) ; at their extremity they expand into 

 Hattened lobes, which spread out on the sui'face of the sea- 

 weed. 



The cells are placed in longitudinal series at the upper parts 

 of tlie branches, the lower portion of which is left bare through- 

 out a greater or less extent. The series of cells are sometimes 

 rlosely crowded and continuous, sometimes interrupted by a 

 few short intervals, whilst in some cases again (in the oldest 

 Ijranches) the cells are placed in only a few'isolated groups. 

 On the youngest terminal ramuscules, the row of cells is 

 usually placed on one side ovAj, as in Ser'tolaria cornuta and 

 fy. lendigera, Lam. ; but in the others they form two series, 

 more or less exactly opposite. 



The cells arc membraneous, and when full grown about 

 O'omm. long, of an attenuated form, diminishing gradually in 

 diameter from 02 to O'l mm. They are seated on a rounded 

 Ijase, in an oblique position, leaning towards the extremity 

 of the brancli; and they are furnished at the summit, where the 

 Mall is continuous with the tentacular sheath, with a cii'clet of 

 delicate, flattened, colourless sette from O'Oi to 005 mm. long. 

 W'lien the polypide is forcibly retracted, fully a third of the 

 cell is inverted, and it then assumes more of an oval shape. 

 The old, uninhabited cells, Avhose summit is always inverted, 

 arc thicker and shorter, and of an ellipsoidal form. 



The animal [polypide] is furnished Mith eight tentacles 



