Reviews — Bather's Crinoidea of Gotland. 133 



posterior radial-plate that traces of bisection ever occur. This 

 new arrangement is put forward tentatively, but the author claims 

 that it is more philosophical than that for which it is substituted. 



Among the many points of interest brought to light by Mr. 

 Bather from the study of the Gotland Crinoids (and of those from 

 the corresponding beds in this country) is the discovery of an anal 

 plate in the dorsal cup of Pisocrinns, which thus determines the 

 posterior interradius and proves the azygous plate to be a true 

 radianal. This involves a complete change in the hitherto received 

 orientation of the calyx plates in this genus, and brings it into 

 harmony with the rest of the Monocyclica. The author proposes to 

 add the genus CaJ ycnnthocrimis to the family Pisocrinidee, as defined 

 by von Zittel, and to remove from it Catillocrinus, Troost, on account 

 of the absence of a radianal plate in this form. 



In the family of the Heterocrinidge are included the genera 

 locrinus. Hall, Heterocrinus, Hall (nan W. and S.), Ectenocriaaa, 

 S. A. Miller, OMocriniis, W. and S., Anomalocrinus, Meek and 

 Worthen, and Herpetocrinus, Salter :=My el odactylus, Hall. This 

 latter is the only genus represented in Gotland, and a nearly 

 complete account of its morphology, mainly based on specimens 

 of H. Fletcheri, Salter, from Dudley as well as from Sweden, is 

 given. This genus is best known from the peculiar manner in 

 which the stems with their two rows of cirri occur coiled up on 

 the surface of the rock, giving a fanciful resemblance to a huge 

 centipede; it is also further noticeable from the curious mistakes 

 which have been made in the determination of fragmentary speci- 

 mens referred to it. The forms first placed in the genus were some 

 ossicles or joints of the stem, which Professor Jas. Hall mistook for 

 portions of the arms and pinnules of the Crinoid, and described them 

 as belonging to a distinct genus, which he named Myelodactijlus. 

 On this error Mr. Bather remarks, that " it should have been clear 

 that the specimens, whatever they were, were not the brachials of a 

 Crinoid ; for the ' tentacles ' were represented as two to each ossicle. 

 Ill no Crinoid is there more than one pinnule to a single brachial : such 

 an occurrence is an evolutionary impossibiliiy." (The italics are the 

 writer's.) Prof. Hall's mistake was pointed out by J. W. Salter, 

 who correctly described the stem and ci'own of the Crinoid, and, 

 on the ground that the name proposed was based on false ideas, 

 substituted for it the name Herpetocrinus. Strangely enough, in 

 the present paper, Mr. Bather describes as the stem of a new 

 species, ITerpetocrinus scolopendra, an open helicoid coil with two 

 short cirri to each ossicle ; this stem is stated " to very closely 

 resemble the arms of a Crinoid with cirri coming off as pinnules ; 

 with this important difference that each ossicle bears two cirri " 

 — which is pronounced above to be an evolutionary impossibility. 

 After this description was printed off, the clearing away of the 

 matrix from the supposed stem and cirri revealed that these bodies 

 were furnished with a ventral groove, and consequently that they 

 were genuine arms, each brachial having a pair of pinnules in spite 

 of the evolutionary impossibility of such a fact. The difficulty, how- 



