28 THE AUSTRALIAN MUSEUM. 



dorsal, on a wide projection. Surface almost wholly covered with a thick 

 layer of sand and shell fragments. Colour of exposed anterior end 

 yellow brown. Length 3'3 cm., breadth (dorso-ventral) 4 cm., thickness 

 3 cm. 



Test thin parchment-like and brittle, but covered \vith a very thick 

 layer (from 5 10 mm.) of matted hairs containing mud and sand grains, 

 and having larger fragments on the exterior. A few slender vessels 

 ramify in the inner layer of the test. 



Mantle yellow and muscular with strong sphincters which are continued 

 as a circular muscle layer over the greater part of the body. Internally 

 there are longitudinal muscle bands radiating from the long branchial and 

 atrial siphons. 



Branchial sac with 6 or 7 folds on each side. About 8 internal 

 longitudinal bars on a fold, and 2 or 3 in the interspace. Usually one 

 wide (about 6 stigmata) and two narrow (about 3 stigmata) rows of 

 meshes between two folds. Stigmata short and rounded, irregular in 

 places. 



Dorsal lamina composed of a row of long, pointed languets, closely- 

 placed. 



Tentacles much branched, about 8 larger and eight smaller. 



Dorsal tubercle small and simple, an elliptical slit in a deep triangular 

 peritubercular area. 



Alimentary canal forming a wide loop. 



Gonads on both sides. 



Locality. Port Jackson ; one specimen. 



There is only one specimen of this species, but it has such a striking 

 form and appearance (PI. Cyn. VII., fig. 4) that it cannot be mistaken for 

 anything else. The long narrow branchial siphon sticks up, free from 

 sand and shells, and the hole in the dorsal projection (fig. 4) probably 

 during life allowed the atrial siphon to protrude in a similar manner. 

 The large shell fragments are all on the surface, and most of them are 

 attached by their edges, so that the sandy test bristles with them. The 

 matted mass of hairs and sand can be peeled off, leaving the thin and 

 brittle true test, which is seen under the microscope to be closely peppered 

 over with the finer sand grains, and to have a few slender vessels 

 ramifying in the interior. 



When the test is removed (fig. 5), the curious shape of the long slender 

 atrial siphon is seen stretching outwards from almost the posterior end 

 of the dorsal edge. The folds of the branchial sac are a little difficult to 

 determine along the edges, although quite distinct in the middle of the 



