784 .T. H. ASHWORTH. 



imperfectly divided into two by a groove; tiie anterior part— the peristomium 



i^Per.) is again partially subdivided into two annnli, in the anterior of which 



the otocyst {01.) may be faintly seen ; the posterior part {A. B. S.) is the first 

 body-segment, which, however, does not bear any traces of seta. The sue- 

 ceedin'^ segments bear notopodial and neuropodial setae. Tlie former usually 

 consist of two or three capilliform bristles and one lanceolate seta (see also 

 pjrrs. 3— fi). The alimentary canal is seen by transparency through the body- 

 wall. The buccal mass leads into the oesophagus, which dilates in the fourtli 

 chfctigerous segment, and in tiie sixth bears the glands {(E. GL), seven of 

 which may be recognised. Immediately behind this the oesophagus is con- 

 tracted, and leads into the stomach, on whose surface the almost rectangular 

 chlorogogenous areas are already differentiated. The nephridiopores arc not 

 shown, as they are too minute to be detected with certainty, x 50. 



Fig. 19.— The anterior end of the same specimen. Ventral aspect. The 

 slit-like ccclomic cavity between the two anterior brain-lobes is seen by trans- 

 parency in the prostomium. The metastomial field— the area included 

 between the oesophageal connectives— is slightly raised above the level of the 

 general epidermis. The specimen shows the peristomium [Per.), the achsetous 

 body-segment {A.B.S.), and the first chsetigerous segment {Ch.Ser/.'). See 

 description of previous figure. Compare these parts with those of tlie adult 

 shown in Fig. 20. X 50. 



Fig. 20.— The anterior end of an adult specimen of A. assimilis, var. 

 affinis, from Otago Harbour. Dorsal aspect. Note the prostomium with 

 its V-shaped lateral lobes embracing the median one. The nuchal groove 

 {Nne. Gr.) and the origin of the metastomial groove {Met. Gr.) are shown. 

 The first ehatigerous segment {Ch. Seg.') consists of three annuli. The region 

 between this and the prostomium is divisible into two almost equal parts, an 

 anterior part— the peribtomium {Per.)— in which the two annuli are not very 

 regular, and a posterior part, consisting of two annuli, which form the acha;- 

 tous body-segment (J.B.S.). X 8. (Cf. Fig. 19.) The form of the pro- 

 stomium and the annulation of the skin of type specimens of A. assimilis 

 from Uschuaia are exactly the same as shown in this figure. 



Fig. 21.— Transverse section of a post-larval specimen of A. assimilis 

 var. affinis, 87 mm. long. The section passes somewhat obliquely through 

 the posterior brain-lobes, the nuchal organ, and the otocyst of the right side 

 The two posterior cerebral lobes {PosL Cer. L.) are seen in the prostomium 

 separated by a portion of the coelomic cavil y. They are closely applied to the 

 nuchal organ, the ciliated epithelium of which is well seen on the left, but is 

 cut obliquely on the right. The right otocyst is seen as an invagination of 

 the epidermis, the mouth of the pit being narrowed to form the tube of the 

 otocyst. Already a few foreign bodies (otoliths) have gained admittance. 

 Note the large gland-cells scattered in the epitiu'lium, tiie sect.ions of the 



