BTBLIOC.RAPHY OF PATi.EOZOTC CRUSTACEA 9 



BEECHER (Cha rles E.)— C ontinued 



This form is similar to the preceding though larger, and with the glabella more 

 rapidly expanding in front. The neck segment is the only one which is distinct. 



Ptychoparia I'lnnarssoni W'alcott, after Matthew. 



The axis is narrow, expanding in front, and obscurely ringed ; 5 annulations be- 

 longing to the head and one to the pygidium, \vhich is very short and separated from 

 the cephalon l)y a distinct groove. 



Ptychoparia k'lngi Meek. 



The author remarks that fig. 6 which is referred to a later stage, shows the incep- 

 tion of several characters that have not as yet appeared in the previous larvae. Tiie 

 axis is very sitrongly annulated ; the anterior lobe is nearly as long as the 4 posterior 

 annulations of the cephalon, and on each side there is a furrow representing the eye 

 line of the adult; the free cheeks are present as narrow marginal plates including the 

 gfnal spines; the pygidium shows 2 segments separated by a furrow. 



The author figures Sao hirsuta Barrande, pi. S, figs. 8-1. 



Ordovician species. 



Triarlhnis hecki Green. 



Two protaspidan stages of this species have been noticed, differing chiefly in the 

 size of the pygidium. Both agree in showing a strongly annulated axis, not expanded 

 in front and terminating some distance within the margin. 



Acidaspis tuherculala Conrad. 



In general form the larvae resembles those of the second larvae stage of Sao, but 

 the pygidium is shorter and the glabella does not expand and terminate in the anterior 

 margin. No eye-line is present, but the eye lobes may be seen a little within the margin. 

 The glabella has the cliaracteristic number of annulations: margin provided with a 

 row of denticles; genal angles extended into spines; pygidium with 4 spines. 



The generic term Arges Cjoldfuss pre-occupied. See Ceratages, Giuich, 1901. 



Arges consangiiinens Clarke. 



As the main details of structure in Acidasipis and Arges are so similar the \'oung 

 Arges show the same acceleration in the development of the spines and surface orna- 

 mentation and the retention of the primitive features of tiie glabella. 



Procliis par-visculus Hall. 



The illustrations of tiiis species sliow strongly annulated axis with groove at each 

 side; large, prominent anterior eyes, pygidial jiieura indicated bv faint grooves. 



Dalmanties socialis Barrande. 



The author gives 4 figures of this species. 



The anaprotaspis stage showing the large, strongly annulaied axis, the prominent 

 anterior marginal eyes, mucronate genal angles. Pygidium of 3 segments. 



Figures 1-8 in the text illustrate the young of A gnustus 7iiiJiis Barr. 



.7. rex Barr., Triniulrus oniatus Sternb., llydroct-pliuliis saliinioijrs Barr. anil //. 

 carens Barr., Olfnellus (M rsonai is) asaphoiJrs Kmnions. 



Tlu' Al()n()[)li()l().uy of 'rriai'lliriis. 



Am. Jour. Sci., ser. 4, vol. 1, No. 4, 1896, pp. 251-256. 

 Geol. Mag., Decade 4, vol. 3, 1896, pp. 193-197, pi. 9. 



Outlines of ;i iialiiral clas.silicatioii of tlic Ti-iloliitcs. 



Part 1, Am. Jour. Sci., ser. 4, vol. 3, 1897, pp. 89-106, plate 3; continued on pp. 

 181-207. 



Order Ilypoparia. 



Free cheeks, forming a continuous marginal ventral plate of the head, and in some 

 forms also extending over the dorsal side at the genal angles. 



Suture ventral marginal, or submarginal. 



