158 Marine Investigations in South Africa. Vol. V. 



calcareous tubes of other animals, even among calcareous algae. 

 (See below for further details.) 



Nervous System. — This is essentially as described in some other 

 species. There are two very fine tracts of punctated nervous 

 tissue running along each side of the body where it is joined by 

 the lateral septa. 



Beneath these, on or in the basement membrane, could be 

 detected a very fine tube, such as has been described. No 

 nervous tissue was found anywhere separated from the epidermis. 

 The specially developed patches of nerve tissue at the base of the 

 lophophore were present as described by Benham (2) for P. australis, 

 and, for reasons stated further on, are perhaps to be considered 

 as olfactory organs. 



Another patch of nervous tissue, apparently representing a sen- 

 sory organ, was found at the base of the epithelium of the floor 

 of the mouth where it joins the transverse septum. The tissue is 

 less developed and definite than in the previous case, but, taken 

 in conjunction with the observations below, it would seem to be 

 an organ of taste, or at least of discrimination of food particles, o 

 which there is a very definite selection and rejection (fig. 6 ne'). 



Musculature. — The longitudinal muscles of the body are fairly 

 well developed. Near the nephridial region they are symmetrical, 

 that is, an equal number on the right and left of the median septum. 

 According to the convenient formula of Longchamps they would be 

 J j^ that is, 12 in the right and left anterior chamber, and 4 in 

 the right and left posterior. This, however, was not constant, and 

 -i\-r and other combinations were observed. 



LophopJioral Organ. — This organ in P. capensis appears to be 

 essentially similar to that in other described species. 



In view of the observations on this organ in the living animal, two 

 parts are to be distinguished. First, the glandular epithelium at the 

 base of the lophophore below the tentacles forming the lower part of 

 the brood chamber. This glandular epithelium extends up on the 

 inner side of one or two of the tentacles, that is, into the region 

 where the more developed embryos lie. It is readily seen in 

 sections that the mucus from the epithelium envelops the eggs, 

 and the mucus with which the mass of developing eggs and embryos 

 are held together is very apparently from this source. Secondly, 

 a free continuation of the epithelium out from the lophophore. 

 The cells here assume rather the characteristic of ordinary 

 epithelium (ciliated). Though in sections little more than a slight 

 projection or fold, this part in the living animal is broad and leaf- 



