NO. 1664. A Nh)W JURAtiSia CRINOrD—HPRINdlJIl. 189 



whitei is similar to that between the recent /. decorus and /. parrcB, 

 which is fairly constant. 



The most nearly related European species that I knftw of is de 

 Loriol's " Pentacrinus " heaugrandi^ from the Upper Jurassic, Port- 

 landian stage, near Boulogne-sur-Mer, France." This was the only 

 Crinoid known to the author from the Portlandian stage, and it is 

 the species which he originally proposed to separate from the other 

 Pentacrinidae on account of having a closed ring of basals, under the 

 name Picteticrinus. In this he found himself anticipated by the 

 Cainocrinvs of Forbes, and in the work last cited, page 281, he aban- 

 doned the distinction, and referred the species to Pentacrinus {sensu 

 P. H. C). It has similar large basals, but the arms branch lower 

 down, the stem is more sharply stellate in corresponding portions, and 

 the cirri much more delicate. The stem is preserved to the fourth in- 

 ternode, which has 8 internodals, whereas ours has 14 at the same stage. 



Pentac7inus {C ainocrinus) andrew Desor'' is similar to the French 

 sjjecies, but wdth shorter basals and shorter internodes. 



The excellent preservation of our specimens enables us to make an 

 interesting comparison with recent species. The stem has a con- 

 siderable resemblance to that of /. decorus^ except in the disposition 

 of the cirri. It must have been quite long, as the longest portion, 

 l)reserved to a distance of 140 mm., shows little sign of any rounding. 

 It is rather more pentagonal for equivalent distances. The cirri are 

 very long and slender; the taper near the base from short and wide 

 joints to long, narrow, and equal ones, is quite marked. The most 

 perfect one has 44 joints, and this was probably near the maximum. 

 The interesting thing about the cirri, however, is the fact that they 

 are directed upward instead of downward or outward. In conse- 

 quence the sockets do not extend to the infranodal (hypozygal) joint, 

 but slope upward toward the supranodal, the lower margin of which 

 is often incised by them. This is more or less the case in the genus 

 Metacrmus, but is not usual in the recent species of Isocrinus, most 

 of which have the cirri directed downward, though in some, as /. 

 asteria and /. wi/nille-thomiioni^ the socket is confined to the nodal 

 joint, and the cirri are given off about horizontally. 



The basals, as shown by the five specimens figured and three others, 

 are quite uniform in their form and proportions. They form with 

 the radials a low funnel, with smooth or slightly rounded sides, and 

 without protuberance or projection of any kind. They are connected 

 exteriorly by their lateral faces, giving a pentagonal outline and 

 forming a closed ring (Plate 4, fig. 3a), as in the type for which 

 Forbes proposed the genus Cahiocrinus, instead of appearing as mere 

 triangular points separated from each other by the radials, and tend- 



«Mon. Etage Jur. BoiiloKne-snr-Mer, 1875, p. 298, pi. xxvi, figs. 23-25; 

 Paleontologie frangaise, CriuoTdes, XI, 2" partie, p. 278, pi. clxxxi, figs. 1-3. 

 * De Loriol, Crin. Foss. de la Suisse, p. 112. 



