256 S. W. Ford—Additional Embryonic Forms of Trilobites. 
the head alone, no one sages acquainted with Primordial 
Trilobites would hesitate to pronounce it a Paradoxides; an 
M. Linnarsson thus unquestioningly describes it It is only 
when we come te compare it with such forms as Olenellus 
Fig. 9—Head (minus the st roars and thorax - Hydrocephalus Saturnoides 
Barrande, enlarged 16 diam Fig. 10.—Plan of structure of the head of 
og ides Kjerulfi rating “from ae Swedish an ordial, nat. size. Fig. 
—Head of Hydroc on ad carens Barrande (the free inieks restored in out- 
tine), enlarged 6 Giaiiete 
asaphoides and QO. Gilberti, and especially with the young of 
the former, that the real diffic aly, arises. It differs from the 
other forms of the genus main] 1) The possession of a 
pair of SpiHOn processes extending sags the neck-furrow back- 
al the stages. 0. a ee further shows its close relation- 
ship with the Swedish form in haying all of its glabellar fur- 
rows, in early embryonic life, extending entirely across, instead 
of being interrupted, as in the more advanced and mature 
forms, on the median taal There can be scarcely a doubt that 
the figure of Paradoxides Kjerulfi above given represents a fully 
developed form, and that all of the characters which it exhibits 
were permanent in it.* 
The above facts, taken in connection with those stated 
earlier, strongly argue eat Olenellus asaphoides may be safely 
regarded as higher in grade than any known form of Paradozx- 
* It is worthy of remark, in this sad — the ons 4 of the eggs 
due to the firm coalescence of the fre d cheeks in front of the 
appears to have characterized all the known eset te) Temellis and that in pole: 
of them at least, 0. i fbaaee cot (fig. 12), th e central Nhe of the fixed cheeks, 
* 
