656 SILUIUAX TUlLumiKS UF NKW SOUTH WALKS, V., 



mere tliickeiiiugs. On the other hand, in the figure of E. pnuc- 

 fafii.s by A. l^rongniart,* these prominences appear to be, in the 

 perfect form, definite tubercles, and, in consequence, this feature 

 does not appear to have generic vahie, although they, too, whether 

 mere thickenings or distinct tubercles, may have been produced 

 by muscular insertions at these points. 



AVe have already stated our disbelief in the presence of glabella 

 furrows in Encriniiruti, i.e., in the perfect testaceous condition. 

 On the other hand, in non-testaceous specimens or "cr/.s^s-," as 

 they are often called, there are short spaces between the axial 

 tubercles winch simulate furrows, but we believe these arise 

 solely, (l)from the projection (^f the tubercles in question into 

 or over the cephalic axial furrows, and (2) by the removal of the 

 test from between them dui'ing the pi'ocess of decay. Hence 

 the size and amount of })rojection of these prominences becomes 

 a specific character. Amongst Australian species, the false 

 furrows are shown at their greatest development in E. efheridc/ei. 

 .Vt tlie same time, should there be a census of opinion that these 

 are true furrows, then we are prepared to admit the identity of 

 Crimius with Encriituru)^, but not otherwise. 



The pygidial axes of all the five species, E. mitchelli, E. boic- 

 ii.uu/e)t,sit>, E. efhfirid(/('i, E. silverdalensis, and E. rothwell(v, in 

 the non-testiferous condition, possess a central longitudinal area 

 across which the anindation grooves are discontinuous; when, 

 liovvever, the test is preserved, in some of these species these 

 annulations are continuous, and no interruption is visible along 

 tlu^ whole length of the pygidial axis. This is the case in some 

 })ygidia froui Bowning, which, at present, we place with E. pfhcr- 

 idi/f'l ; and some pygidia from Duntroon are similar in this 

 respect. In E. ntlfchr/li, testaceous specimens indicate continuity 

 of the pygidial axial anindations. E. howniru/efisi.s and E. silvr7'- 

 daleitm.s appear to possess a well marked central axial area on 

 their })ygi(lia e\iMi in the testaceous state, and in this i-esemble 

 E. pii ncf<(fiis. These \ariations ai'e of s})ecific value. 



* A. Broiigiiiart, Hist. Nat. Crust. Foss.: Les Tri.lobites, 1822, PI. i., 

 Hg.8A (rts Calymene oariolaris). 



