798 ON THE CH.ET080MATID.E, 



and, at its junction with the uterus, is surrounded by a few large 



cells, which probably act as a sphincter (Fig. 47, ^v/.). The de- 

 velopment of the fertilised ovum has not been followed. 



Type-specimens, Nos.W, 454, 455; in the Australian 

 Museum, Sydney. 



Ch(i4ot<oma hasirelli, ii.sp. Measurements in mms. 



? c^ 



Total length ^ ... 1-39 ri28 



Length of head * ... 0-144 OTiO 



Length of trunk r'248 r008 



Length of trunk covered by rows of seta? 0*185 0'166 



Length from tip of tail to ant. end of rows of setie... 0'383 0'383 



Length from tip of tail to aims 0*092 (riOT 



Length of tail O'CST O'dST 



Length from neck to genital pore 0*600 — 



Greatest width of head 0*070 0*066 



Greatest width of trunk 0*08r) 0*059 



Width at level of ventral seta? 0*047 0*030 



Width at level of neck-constriction 0*029 0*033 



Length of rostrum *026 *022 



Length of seta? on rostrum 0*022 '022 



Length of hairs on trunk 0*037 0*025 



Length of ventral sette, outer rows 0*044 0*055 



Number of setit? in ventral rows — outer 13 7 + 4 



inner ... ... 15 12 



The two species, included in this genus, differ considerably 

 from any of the Chietosomatidft! hitherto described, in that a 

 well marked head-swelling is absent. There is a corresponding 

 difference in the structure of the pharynx, which lacks the typical 

 pharyngeal bulbs, and is only slightly swollen posteriorly. The 

 structure otherwise is very similar to that of the Chf^tosomatidie, 

 but the differences indicated seem to be of sutticient importance 

 to constitute a new genus of this family. 



Genotype, iV". tenax, n.sp. 



NoTOCH^TOSOMA TENAX, g. et sp.nov. (Platcs xlviii.-xlix.). 

 Only a few specimens have, so far, been obtained, all taken 

 from a single locality in Port Jackson. I first found four in the 



