370 MR. J. D. MACDONALD ON THE ANATOMICAL CHARACTERS 



cii'cular muscular fibres, while others are scantily distributed in various directions over 

 the body. 



The branchial network is very delicate and rests upon a stout transparent membrane, 

 which is sacculated or embossed towards the respu-atory cavity. 



The internal tentacula are compound, as in the former species ; and the mouth, stomach, 

 intestine, testes, and ovaria exhibit the same general disposition, so that the description of 

 those organs above given wUl equally apply to the present case, with the following excep- 

 tions, namely, that the stomach in the latter is covered with a very dark pigmentary 

 matter, probably including biliary foUicles, and the intestinal loop is more open, so that 

 the right testis and ovarium lie within it. 



Finally, the heart holds a slightly oblique position below the left ovarium, and rests on 

 a curved cylindroid body tinted with a rich madder-brown pigment, unquestionably the 

 equivalent of the organ which I have assumed to be an " elceoblast " in the last-described 

 species. 



June 1858. 



EXPLANATION OP THE PLATE. 

 Tab. LXIV. 



[The same general references apply to all.] 



I. Ceesira parasitica. King George's Sound species. 



Fig. 1 . Animal in situ, with a cluster of zooids of Perophora Hutchisoni. 



a. Branchial, and 



b. Cloacal opening (both being contracted and radiately puckered). 

 Fig. 2. The animal removed from the test, to show its internal parts. 



c. Nervous ganglion. 



d. Position of the mouth. 



e. Stomach, and e'. Liver. 



/. Intestinal canal and loop. 



g. Rectum. 



h. Right testis. 



i. Right ovarium. 

 Fig. 3. Simple external tentacula, magnified. 

 Fig. 4. One of the compound internal teatacula. 

 Fig. 5. Immature ova. 

 Fig. 6. Perfect ovum with additional yelk-granules and outer covering. 



II. C.Jicus. Shark Bay species (No. 1). 

 Fig. 1. The animal as it appears in its natural state, with one or two Sertularians growing on its 

 granular coat. 



