812 ON THE CH.ETO.SOMATID.E , 



c . Setfi? of ventral rows compound C. dapartdii. 



cc. Settt of ventral rows simple, and very delicate... 6'. macrocepha/um. 

 aa. More than two rows of ventral seta". 

 d. With three rows of ventral seta^. 



e. Inadequatelj^ described species C. [ir<i^nkiudiciim. 



ee. Recoij;nisable species. 

 f. Rostrum short and strai^^ht; head-seta^ poorly developed, 



and not hook-like C. trixtlcocheta. 



ff. Rostrum very long and sharplj' bent in a ventral direction; 



head-setje well-developed and hook-like C. loiKjirosfrum. 



dd. With four rows of ventral seta?. 



g. With a conspicuous band of transverse stride behind rostrum. 

 h. With onlj^ one roM' of dorsal head-seta?; rostrum provided 



with spines C. spinosum. 



hh. "With more than one row of dorsal head-seta?; rostrum not 

 provided with spines. 

 /. With two row^s of dorsal head-setae; trunk-hairs arranged 



in eight longitudinal rows C. ha-sirtlli. 



n. With three rows of dorsal head-seta; trunk-hairs arranged 



in six longitudinal rows C. hiheniicnm . 



gg. Without a conspicuous band of transverse stria? behind rostrum. 

 /. With three rows of dorsal head-sette; rows of trunk-setw 



very long, extending halfway vip trunk C. falcutum. 



Key to the Species of the Genus XotocJuetoi^otna. 

 a. Dorsal head-set;e not inserted on rostrum; tail not serrated . X. tenax. 

 aa. Dorsal head-sette inserted on rostrum; tail serrated along ventral 



surface X. cryjAoa^phaliim. 



All tlie figures, for both Plates and Text-figures, were drawn 

 with tlie lielp of the camera lucicla, the finished drawings being- 

 prepared by Mr. F. AV. Aitkins, of the Technical High School, 

 Sydney. 



LITERATURE. 



1. Clai'.\kei)K, R. — Beobachtungrn iiber Anatomic und Entwickelungs- 



geschichte wirbelloser Thiere, u.s.w. Leipzig, 1863. 



2. Metsch>'IKOff, E. — "Beitrage zur Naturgeschichte der Wiirmer, i. 



Ueber Cluvitosoma und Rhabdogaster." Zeitschr. f. wiss. Zool., 

 xvii., 1867. 



3. (4keef, R, — " Untersuchungen iiber einige merkwiirdige Formen des 



Arthropoden- und Wurm-typus."' Arch. f. Naturgesch., Jahrg. 35, 

 Bd. i., 1869. 



