188 W. BLAXLAND BENHAM, 
escaped the notice of naturalists since that time. To it he 
gave the name Heterocheta costata; the generic name 
referring to the interesting arrangement of chet, and the 
specific to longitudinal ridges, or to the distinctly annulate 
character of the segments. 
Of these worms I found abundant specimens in some of the 
earlier gatherings (in May) ; but more recently, in the latter 
end of June, I have been able to find only a few specimens, 
though I still find a few fully mature forms now in July. 
Heterocheta costata, Claparéde, 1863. 
In his studies on Invertebrates from the coast of Normandy 
(‘Beobach. u. Anat. und Entwickel. wirbelléser Thiere ’) 
Claparéde gives (p. 25) a brief diagnosis of a new genus, of 
which the following is a translation : 
“Heterocheta, n. gen. 
“‘Chzetze bundles in two rows (on each side) ; those of the 
upper row, on Segments v to vii, are hollowed out at the free 
end in the form of acup. The remaining chetz are all crotchet- 
shaped [hakenformig]. 
“H. costata, n. sp., Taf. xii, figs. 16 to 19. 
“ Body 16 mm. in length, 4 mm. in breadth; skin ribbed 
by longitudinal grooves ; each segment divided into rings by 
about four constrictions.” 
He further states, during a brief extension of the diagnosis, 
occupying only eight lines, that all his specimens were 
immature and without a clitellum ; that the peculiar chetz 
(which he figures) have a constriction just below the cup 
(or “becher”); that the ordinary cheta has a swelling (or 
“ node,” as I will call it) about midway along its length. The 
vascular system consists of a dorsal vessel, a ventral vessel, 
and a loop in each of the hinder segments. 
This is essentially all that is known of this interesting worm ; 
