344 THE LIAS AMMONITES. 



fine specimens have likewise been collected from similar beds at Robin Hood's Bay, York- 

 shire, where Sowerby's type Avas found. I have found fragments of this species in the same 

 zone in some exposures of the Aeg. Jameb-oni-heds near Cheltenham. 



Aegoceras Milleri, TFri^/a, nov. sp. PI. XXXVH, figs. 10, 11. 



Diagnosis. — Ammonite large, depressed, flattened on the sides, and slightly involute ; 

 shell very thin, not thicker than fine cardboard ; whorls broad, much flattened across the 

 siphonal area, vertical height two thirds that of the transverse diameter, sides with slight 

 undulations, terminating in short tubular blunt knobs on the margin ; the siphonal area 

 and sides of the tubercles sculptured with a series of longitudinal elevations and depres- 

 sions, which impart an ornate character to this region of the shell, and form a good 

 specific feature for the distinction of the species. 



The size of this Ammonite is unknown, seeing that fragments only have been found, 

 the whorls being so slightly involute that no disc will hold together. 



This species resembles Ae^. muticum in the position, form, and size of the tubercles, 

 and likewise in the small amount of its involution ; it differs from Aeg. muticum, however, 

 in the absence of longitudinal striae on the siphonal area (see fig. 10). The lateral view of 

 the whorl (fig. 11) shows the arrangement of the tubercles on the margin of the area. 



Locality and Stratigraphical Position. — This fragment was collected by Professor 

 Archibald Geikie, F.R.S., in Pabba, along with other fossils from the zone of Aegoceras 

 Jamesoni sent by my friend to me to determine. Prof. Geikie at the same time requested 

 that, should I meet with any new forms in the collection he had made, I should associate 

 the name of Hugh Miller, of the Old Red Sandstone, with the Pabba beds as a memento 

 of the valuable work he carried out by his researches among the Hebridean Lias beds in 

 his cruise in the ' Betsey '; in compliance with my friend's request, and with very great 

 pleasure in doing so, I dedicate this singular Ammonite to the memory of Hugh Miller. 



Aegoceras Leckenbyi, Wright, nov. sp. PL XXX, figs. 1 — 7. 



Diagnosis. — Shell discoidal, with rounded whorls, one third involute, and a wide open 

 umbilicus ; sides of the whorls ornamented with primary and secondary ribs ; the 

 primaries vary from twelve to twenty-four in number, they are larger in size, and each 

 rib develops a blunt elongated tubercle near the siphonal area and sends several smaller 

 branches therefrom across the area ; and the secondaries consist of numerous smaller 

 sigmoidal annular radii interposed between the primaries, encircling this region which 



