Correspondence — Mr. F. A. Bather. 381 



SCOZOCFSTIS, ECEINOCYSTIS, AND LTSOGYSTIS : DISCOGYSTIS, 

 ECEINODISCUS, AND AGELACKINID^. 



Sir, — In his valuable paper " On Ecliinocystis and PalcBodiscufi " 

 (Quart. Journ. Geol. Soc, liii, 123-36, pi. vii, February, 1897), 

 Dr. J. W. Gregory has a footnote (p. 133) that may, if not emended, 

 give others as much trouble as it has given me. "To save further 

 confusion" Dr. Gregory proposes the name Scolocysfis for an obscure 

 cystid to which the preoccupied name EcJiinocystis was given by 

 Hall. We are not told what Hall, what species, or in what 

 publication, although a mysterious thing called " Hall's date " is 

 discussed. My friend Dr. Gregory kindly allows me to say that 

 the reference is to Echiiiocystites nodosus, James Hall, " Account of 

 some new or little-known species of fossils from .... the 

 Niagara group," 20th Rep. N.Y. State Cab. Nat. Hist., p. 316, 1867, 

 also published in advance as part of 18th Eep., December, 1864, and 

 January, 1865, as well as on p. 360 of Revised Edition, 1870. 



Having this information, it is easy to see that the acute Mr. S. A. 

 Miller, in his most useful work, " North American Geology and 

 Palseontology " (1889), to which it is the duty of every writer on 

 American fossils to refer, has anticipated Dr. Gregory, and has there 

 proposed the name Lysocystites for the genus of E. nodosus. 



There is another generic name proposed by Dr. Gregory on p. 131 

 of his paper, viz. Discocystis : this, too, requires some comment. 

 Dr. Gregory argues that Palfsodiscus and Echinocystis are true 

 echinoids, having no connection with the Agelacrinidas. " There 

 is, however," he says, " one genus which, if correctly described by 

 Worthen and Miller, may be a Carboniferous rej)resentative of either 

 Paloiodiscus or Echinocystis [and therefore an echinoid]. According 

 to the description of its authors, this remarkable form has an 

 irregular, sac-like body ; above the mouth there is a series of 

 plates which may represent jaws [i.e. echinoid jaws]. The name 

 Echinodiscus was given to this fossil by Worthen and Millei', but this 

 term having been preoccupied by Agassiz for an echinid, for which it 

 is still in use, the name of the cystid may be changed to Discocystis.'^ 



If Dr. Gregory considers Echinodiscus optatus (for that is the 

 species to which he is referring) to be an echinoid, perhaps he will 

 explain why he calls it a cystid and Discocystis. That it is a cystid 

 and no echinoid at all, is my firm belief; and had Dr. Gregory been 

 better acquainted with the writings of Mr. S. A. Miller, we should 

 probably have had neither the above enigmatic paragraph nor the 

 name Discocystis. At all events no one has any business to fling 

 names about in this reckless way without considering all the facte and 

 possibilities of the case. Three species have been referred to this 

 genus, and should all have been reckoned with by my onomatopoeic 

 friend. They are : E. optatus, Worthen and Miller (1883), the type- 

 species; Agelacrinus Tcaskashiensis, Hall ("Geol. Iowa," i (2), 696, 

 1858), referred to Echinodiscus by S. A. Miller ("N. Amer. Geol."); 

 and E. Sampsoni, S. A. Miller (17th Eep. Geol. Surv. Indiana, p. 76, 

 1891). Comparison of these shows plainly that they belong to the 

 Agelacrinid^. The "' mouth," which Dr. Gregory innocently quotes, 



