BIBLIOGRAPHY OF PAL.IiOZ(JlC CRUSTACEA 81 



RAYMOND (Percy E)— Continued 



The author remarks on the order Hypoparia in Beeclier's classification. Since the 

 young of practical!}' ail primitive Trilobitcs lack eyes on the dorsal side, Beecher 

 grouped all Trilohites in which absence of eves was a primary characteristic in his 

 First Order, Hypoparia. Recent studies and discoveries have led a number of in- 

 vestigators to the conclusion that blindness in the Agnostidae, Eodiscidae, Trinu- 

 cleidae, Raphiophoridae and Harpedidae is secondary and a degenerative not primitive 

 characteristic. If their position is well taken, then the order should disappear and the 

 families be distributed in the two orders which remain. 



The author gives a figure of Aviinstus r.udtts exhibiting tiie facial suture and free 

 cheeks. The facial sutures are not marginal, but intra-marginal. They meet in an 

 obtuse angle at the front and run backward just inside the margin, somewhat like the 

 course of the pre-ocular portion of the suture in an Homalonotus. The sutures keep 

 within the angles, so that the fixed cheeks bear the genal angles — a Proparian char- 

 acteristic. The sutures in this manner cut oif a yoke-shaped area, bounded outside by 

 the facial sutures and inside by a marginal edge, which follows the outline of the 

 base of the elevated portion of the cranidium (tlie glabella). Both limbs of the yoke 

 taper backward to a point, and it forms a continuous plate, with no vertical or 

 epistomal sutures. This plate has the position and aspect of a large epistomal plate, 

 but, whether called an epistoma or free cheek, the sutiues which separate it from the 

 cranidium must be interpreted as the facial sutures. 



The author includes only one family under Hypoparia, that of Eodiscidae, Eodiscus 

 as defined by Matthew, 1S96, Mollisonia Wale, and Pagetia Wale. The discovery of 

 Pa^cria I'ootes and P. clytia, which bear eyes very close to the lateral margins, seems 

 lo be a confirmation of the previous supposition that the Eodoscidae have ventral free 

 cheeks. 



Dr. Raymond does not note Microiihciis caitdafns Delgado, a species with a mn- 

 cronated pygidium and \vith free cheeks, from the Cambrian of Portugal. 



Delgado's description, p. 349, pi. 3, fig. 12, Fauna Cambrian Haut Alemtejo. 



Remarks: "La suture faciale, mais il semble que a partir de Tangle anterieur de 

 I'oeil; il decrit une courbe tres courbe, ayant la convexite tournee en dehors, allant 

 trav'erser le contour exterieur de la tete pres de la projection de I'oeil; posterieuremcnt 

 il decrit aussi une courbe analogue, atteignant le contour interieur en dedans de la 

 projection posterieure du centre de figure de I'oeil." 



I would suggest the new genus Delgadoia for this species as a type. 



Dr. Raymond remarks on Shumardidae, that tliese little trilohites are t(K> much of a 

 puzzle to be discussed at any length. 



The paper ends in a discussion of Harpedidae and Trinucleidae. 



T^he author would not include Orometopus in the last family, and remarks: "It is 

 so unlike any of the Trinucleidae, that the burden of proof that it belongs to that 

 family should be upon those who placed if there." 



Uiuier Raphiophoridae, a figure of l.onchodomas portlocki Barr., \vhicli shows on 

 the ventral side of the head, a yoke-like plate similar to that of .l^riosliis tiuJus, but 

 instead of being confined to the ventral side it laps over the margins up onto the dorsal 

 side, being separated from the cranidium by a suture which has the course of the or- 

 dSnary facial suture. The absence of eyes makes the analogy with the ventral plate 

 of Agnostus the more complete. 



Having reviewed all the families of llie Hyjiopaiia the author remarks that there 

 seems to be a tendency in two directions — in Agnostus and Eodiscidae towards the Pro- 

 paria, and in the Trinucleidae and Raphiophoridae towards the Opisthoparia. 



Mesonacidae : 



The author remarks there can be no doubt that Hllif>lo(Cf>/i(ilti /i.uif'/ioidrs and other 



