REPORT OF THE DIRECTOR I9IO 255 



edges of a short series of basal brachiolar plates or armlet ossicles. 

 These plates have wedge-shaped insertions and reach nearly or quite 

 through to the inner surface of the theca. The brachioles or arm- 

 lets next to the mouth are large and long and may have been com- 

 pound. As their distance from the mouth increases, their diameter 

 and length rapidly decrease (see text fig. 35). The plates of the 

 theca are reduced on the anterior side to nearly or quite three par- 

 tial circlets. The posterior area is much inflated and requires some 

 five to seven or more plates to reach from the stem to the orals. 

 Stem narrow, short and wxak and not able to support theca. 



Differs from Malocystites Billings in that its armlet or brachiole- 

 bearing plates do not run over the surfaces of other thecal plates 

 and across their sutures but are, on the contrary, raised into a higher 

 food-collecting territory and are capable of considerable adjust- 

 ment (a modification necessitated by loss of supporting stem). The 

 sigma, with its short arms and the rapidly changing size of its basal 

 armlet ossicles, is in itself a sufficient distinguishing character. In 

 Sigmacystis anterior plate reduction has progressed farther than in 

 Malocystites and the mouth has thus been drawn farther over toward 

 the proximal stem joint. 



The specimen described as Malocystites emmonsi in 

 the Report of the State Paleontologist for 1903, there designated 

 as ''specimen C" and figured on page 276 and again in plate i, 

 figure 7, is now made the hologenotype of Sigmacystis. The neces- 

 sity for a new generic name for these forms was also recognized 

 independently by Dr Percy E. Raymond. While my name was in 

 manuscript he kindly loaned me his entire pelmatozoan collections 

 from the Chazy beds and I find there these forms given the practi- 

 cally identical name of Sigmacystites. Malocystites mur- 

 c h i s o n i Billings remains the genotype for Malocystites. 



In Canadian Organic Remains, Dec. Ill, p. 66, Mr Billings calls 

 attention to the absence of evident pores in the plates of these 

 genera and compares his Alalocystites with Cryptocrinus von Buch. 

 Through the courtesy of Doctor Whiteaves I was loaned a box 

 containing two cystids collected by Mr Billings and labeled '' Cryp- 

 tocrinus, Chazy, near St Michel, E. B. 1857."' ^^^ of these is a 

 well-preserved specimen of Sigmacystis emmonsi and its 

 plate analysis is given in text figure 36. This species is presented 

 here in advance of a more detailed study of the group for the pur- 

 pose of lending emphasis to the point made with reference to the 

 origin of pentamerous symmetry. 



