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RAYMOND: NOTES ON THE ONTOGENY OF PARADOXIDES. 233 
specimen, only 11 mm. long, should be so like the adult. The chief 
differences are that the eyes are slightly longer, the genal spines arise 
further forward on the head, and the terminal spines of the second 
thoracic segment are much longer. These terminal spines of the 
second segment seem the most persistent of the juvenile characters, 
and as has already been stated, all the Bohemian species have some 
remnant of these spines in the adult stage. 
The youngest specimen of P. bohemicus yet seen is that figured by 
Barrande (Loc. cit., pl. 10, fig. 25). It is 14 mm. long, not including 
spines, and exhibits only two youthful characteristics. The eyes are 
long, and the terminal spines of the second thoracic segment are 
greatly prolonged. The glabella shows only two furrows (Nos. 3 and 4) 
the same as in the adult. 
Outside Bohemia young Paradoxides are evidently exceedingly 
rare and have been figured only incidentally. Nothing except a few 
cranidia seems to have been found. 
Scandinana. 
The youngest Scandinavian specimen known is that figured by 
Linnarsson as the type of his species P. aculeatus. This is a cranidium 
slightly less than 2 mm. long from the Paradowides oelandicus zone 
of Borgholm. There is a relatively wide brim in front of the glabella, 
the palpebral lobes extend from the second glabellar lobes to the pos- 
terior margin, intergenal spines are present, the glabella is long and 
narrow, expands slightly forward and has four pairs of glabellar fur- 
rows. It resembles a young Paradoxides more than Hydrocephalus 
saturnoides does, as the glabella is of a more normal shape. This 
specimen * is probably the young of either P. sjogreni or P. oelandicus, 
more likely of the former, as Linnarsson figures another small crani- 
dium 5.5 mm. long which he refers to that species, though with doubt. 
This latter specimen also has a wide brim and four pairs of furrows. 
The adults of both P. sjogrent and P. oelandicus have a narrow border, 
and the glabella almost touches the rim. 
Great Britain. 
Salter figures (Quart. journ. geol. soc., 1869, 25, pl. 3, fig. 8-10) 
three young specimens of Paradoxides hickst. These specimens are 
1 Lindstroem considers this the young of P. oelandicus. K. Svensk. vet.-akad. 
Handl., 1901, 34, no. 8, p. 17. 
