254 RECORDS OF THE AUSTRALIAN MUSEUM. 



Grassi, possess certain characters noted by Dr. T. Krumbach, 11 

 which are very similar to what occurs in this species. S. sibogce, 

 Fowler, judging from a sketch of the tip of a jaw, seems to 

 approach even more nearly. The base of the point is oval, 

 and the pulp is situated nearer the back than the front edge, 

 but not as closely as in S. furcata. The pulp reaches further 

 towards the tip than is figured in other species. The shaft 

 bears neither crest nor serrations. The outermost jaws are 

 longest, being nearly a millimetre in length, and most curved. 

 Their bases are relatively small. The youngest are only about 

 025 mm. long, and are least curved. They possess a large basal 

 part (PI. lxxi., tigs. 2, 3, 4). 



There are two rows of teeth, the anterior containing from six 

 to twelve, the posterior seven to eleven. These teeth are fairly 

 long and strong, the points being small and sharp, especially in 

 the case of those belonging to the posterior row. The inmost 

 tooth of this row measured 079 mm. long, -013 mm. being the 

 greatest breadth (PI. lxxi., tig. 2). 



The vestibular ridge is rather high and hears a number of low 

 rounded papillae. It ends in a prominent lateral process. The 

 whole structure does not extend as far outwards as the tooth row, 

 two posterior teeth being situated quite externally to it (PI. lxxi., 

 fig. 5). 



A satisfactory account of the nervous and sensory systems 

 cannot be given here, on account of the imperfect preservation. 

 Neither optic nerves nor eyes are recognisable with any degree 

 of certainty. The position of the brain is outlined on PI. lxxi., 

 fig. 2. The buccal nerves could be traced only a little distance. 

 The ventral ganglion is rather long and broad. It lies between 

 the epidermis and the muscle layer. The corona ciliata has 

 disappeared from all specimens. One specimen shows a structure 

 which may be a remnant of that organ. 



The body wall consists of the usual layers, (a) epidermis, (b) 

 muscle layer, and, internally, (c) the coelomic epithelium. There 

 is a very delicate basement membrane between (a) and (b). The 

 muscles are arranged in four bundles, two dorso-lateral and two 

 ventro-lateral, each pair being separated along the mid-dorsal 

 and mid-ventral lines respectively by the mesentery. The indivi- 

 dual muscle fibres are easily recognisable. The oblique and 

 transverse muscles of the head, whose function is to move the 

 jaws, are powerful. 



11 Krumbach— Zoolog. Jahrb. Abth. Syst., xviii., 1903, p. 579. 



