248 NEW YORK STATE MUSEUM 



Monograptus Sagittarius Whitfield. Am. Jour. Sci. Ser. 3. 1883. 26:380 

 Didymograptus Sagittarius (Hall) Lapworth. Roy. Soc. Can. Trans, v. 5, sec. 



4. 1886. p.iSof, i83f 

 Didymograptus cf. Sagittarius (Hall) Lapworth. Geol. Sur. Can. An. Rep't. 



Ser. 2, v. 3, pt 1. 1889. P.95B 

 Didymograptus Sagittarius Walcott. Geol. Soc. Am. Bui. 1890. 1:338 

 Didymograptus Sagittarius Gurley. Geol. Sur. Ark. An. Rep't. 1892. 3:411 

 Didymograpsus s a g i 1 1 i c a u 1 i s Gurley. Jour. Geol. 1896. 4:68 

 Didymograpsus convexus Gurley. Ibid. p. 67; pi. 5, fig. 8 

 Didymograptus Sagittarius Dale. U. S. Geol. Sur. Bui. 242. 1904. p. 33 



Hall has, in the first-cited publication, identified a graptolite from 

 the Normanskill shale of the neighborhood of Albany with Prionotus 

 Sagittarius Hisinger. Lapworth recognizing the specific distinction 

 of the two forms hashenceforth cited the American species as Didymo- 

 graptus Sagittarius (Hall). Gurley has proposed [1896, p. 68] the 

 new name, " sag i 1 1 i c au 1 i s," to clear the synonymy ; at the same time 

 suggesting that "very possibly the species is a distal fragment of one of the 

 others in the same beds, but if so, it is so far distal that the chances of con- 

 necting it with the proximal portion are rather small." An inspection of 

 Hall's types — long fragments of branches — which are in the New York 

 State Museum, leaves no doubt that they combine remarkable width 

 (2.9 mm) with absence of an appreciable difference in width between the 

 ends and hence are quite apparently far distal portions of a gigantic form. 

 The shales of Mount Moreno have now furnished fragments of great length 

 (fig. 151, 152 are enlargements of parts of one, 31 cm long) and these exhibit 

 a gradual widening and distinctly connect in their characters and dimensions 

 the thinner branches among Hall's types with the distal portion of a 

 rhabdosome described by Gurley [1896, p. 67] as D. convexus [see 

 fig. 154]. Dr Gurley himself suspected this connection for he remarks: 

 "Possibly it may be the proximal portion of I). s agi ttic aul i s, but 

 nearly fifty years have passed since the discovery of that species without 

 the finding of any specimens long enough to connect the distal and proxi- 

 mal parts; hence the necessity for two names, at least pending the proof 

 of such a connection which may be long delayed. ' It is very doubtful that 



