296 The American Geologist. ^^^>'' ^^o*- 
rule of composition in that language the connecting vowel i 
should be used. The same construction holds in the case of 
Aviculipinna, Pernipectcn, etc. 
Following the definition given by Woodward in the first and sub- 
sequent editions are Tryon (1882), De Koninck (Faune du Calcaire 
Canbonifere de la Belgique, iii, cnq. part, 1885, p. 210), Fischer (1887), 
Zittel CGnindziige, 1895), Zittel (iqoo). Following the definition given 
by McCoy in the original and subsequent works are Zittel (1881-5), 
Hocrnes (1884), Nicholson .(1889), and Steinmann and Doederlein 
(1800). Miller (18S9) includes in his definition of Aviculipecten both 
types of structure, and in this I suspect he is probably right. These 
works rirc for the niost part compilations. I have oeen able to find 
very few discussions cf the genus based upon actual observation of 
ch.nTiclers. a ciivuin;ti.:ice doubtless due to the rarity with which these 
.=;liclls are so jM-rserved as to show the characters of hinge and interior. 
It was nianifeslly impossible to examine more than a comparitivcly 
small number of the works in which this genus is discussed, the major- 
ity of those referi-ed to being textbooks. Some of the different points 
of usage are shown by the following statement : McCoy (Ann. and 
Mag. Nat. Hist., vol. 7, 1851, p. 171) names no type and gives an 
anonymous structural figure which proves to belong to Avicitlih-^cten 
docens; A. Uexuosus Woodward (Man. Mollusca. pt. 2, 1854, p. 262 — 
•Aso in later editions — ) gives no figures and designates Pcctcn gran- 
osiis Sowcrby us the type; Zittel (Handbuck der Palaeontologie. abth. 
I, vol. 2, 1881-5, p. 31) figures A. papyracciis and cites as examples 
A. docens McCoy and A. concavits McCoy; Hoernes (E'emente der 
Palaeontologie, 1884) designates no type, but figures A. papyrciccus 
Sow.; Tryon 'Siructural and Systematic Conchology, vol. 3, 18.34. P- 
291) mentions ?nd figures A. graiiosus as if the genotj-pe , Fischer 
(Man. de Conchyliologie, 1887, p. 947) figures A. papyraceous, and 
cites as an example A. granosus Sow.; Nicholson (Manual of 
Palreontology, vol. i. 1889, p. 701) designates no type, and 
reproduces McCoy's crigmal anonymous structural figure; M'Her 
(North American Geology and Paleontology, 1889, p. 465) gives no 
figures <ind cites as the type A. docens; Steinman and Doderlein 
(Elemente der PaLxontologie, 1890. p. 282) figure no representative of 
the genus and cite only A. papyraccns Sow.; Zittel (Grundziige der 
Palaeontologie, 1895, p. 261) cites no type, or other representation, but 
figures A. papyraccns ; Zittel (Textbook of Palaeontology, vol.- i, 1900, 
■ p. 380) mentions no t.vpe, but illustrates the genus by a figure of A. 
papyracrtis. 
