Hyatt.] 322 [April 4, 



specimen in the Col. Mus. Comp. Zool. either identical or closely 

 allied to Spor. bidens exhibits primitive saddles incompletely 

 divided although the shell is about 4.3 cent, in diameter. The 

 ventral lobes, and the first pair of marginal lobes are still com- 

 paratively small and are elevated upon the large primitive, larval 

 saddles. This genus also as in the preceding shows two dorsal 

 saddles which arise in correlation with the formation of the 

 additional second pair of saddles, and are connected with them 

 by ridges traversing the septa. The first pair of saddles have no 

 correspondents on the dorsum. Sandberger's figure of Spor. 

 bidens, pi. 8, fig. 11, illustrates these observations completely. 

 The annular lobe is deep and undivided. Spor. (Gon.) bidens, 

 sp., Sandb., pi. 8, fig. 11, bilanceolatum, ibid., pi. 9, fig. 7, and 

 Spor. (Gon.) contiguum, sp. Munst. Clym. et. Gon. pi. 3, fig. 8, 

 orbiculare, ibid, pi. 5, fig. 4, cucullatum, sp. Von Buch, Gon. et 

 Clym. pi. 1, fig. 4, Hoeninghausi, sp. Von Buch. Ueber Amm. et 

 Gon. and Mumteri, ibid, pi. 2 ; fig. 4, 5, also Sand. pi. 5, fig. 2, 

 are examples of this genus. Type, Spor. bidens, sp. Sandb. 



Glyphioceratidae. 



This family includes forms having whorls semilunar in section 

 and discoidal shells, with some more compressed and involute 

 forms. The ventral lobes are undivided in the lower transitional 

 forms which connect the family directly with Parodiceras, among 

 the Magnosellaridae, but in the higher genera they are divided by 

 siphonal saddles with cloiochoanitic funnel lobes. The first or 

 primitive saddles are on the venter, the first or primitive lateral 

 lobes are contracted in breadth, deep, and often angular, the 

 magnosellarian saddles are undivided in some genera and divided 

 in others by a single pair of wide, shallow, angular lobes. The 

 primitive, or first pair of saddles have corresponding saddles on the 

 dorsum, on either side of the deep, undivided, annular lobes. The 

 development and outlines of the sutures, and the ventral lobes ex- 

 hibit the close affinities of this family for the Magnosellaridae, and 

 the still younger stages, as described by Branco, show their afiini- 

 ties for the Nautilinidae, especially Anarcestes. 



The septa are convex along the median line, in all the genera 

 except in the transitional genus Brancoceras. The development 

 of the siphonal saddles is similar to that of the Primordialidae, but 



