68 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
genus ; Ophiopus has very rudimentary bursae, while Ophiocymbium 
cavemosum and Opliiothamnus vicarius have true bursae ; as to the dis- 
tinction drawn by Lyman between a “ crease ” and a “ bursa,” it does 
not exist morphologically. 
The opening of the ovary of Ophiopus is at its tip, and is formed 
below the first ripe egg ; the openings are not surrounded by epithelium ; 
as they are formed there is an absorption of a calcareous plate and 
rupture of the fibrillar connective tissue. Herr Morten sen thinks that 
this species never attains a larger size than a disc-diameter of 5 mm. ; 
it is only sexually mature once, and dies after oviposition. 
Silurian Crinoids.* — Mr. F. A. Bather begins a detailed study of 
“ The Crinoidea of Gotland,” with “ Part I. The Crinoidea Inadunata,” 
in which forty species, belonging to ten genera, are systematically de- 
scribed. The work supplements and corrects the Iconographia Cri- 
noideorum, &c. of Angelin, which is regarded as “ splendide mendax ” ; 
but its chief interest lies in the morphological details described and 
illustrated. The discovery of the anal tube of Eisocrinus necessitates a 
fresh orientation of the radii in this and allied genera. Similarly an 
investigation of the evolution of the Calceocrinidae, based largely on 
specimens from rocks in America older than those of Gotland, shows how 
this aberrant family can be brought into line with the Heterocrinidae. 
The structure of the cup in Herpetocrinus is correctly described for the 
first time, and the minute structure of its peculiarly modified stem is 
illustrated and explained. It now seems certain that many of the 
Inadunata with Monocyclic base are all built upon one plan, having 
certain radial s bisected and not others. Such genera were formerly 
supposed to differ in fundamental structure and were divided between 
Larviformia and Fistulata. The author considers that such a division 
has no logical basis, and prefers to erect the suborders of Inadunata 
“Dicyclica” and “ Monocyclica.” Apart from questions of homology, 
minor points of morphological importance are described for the Calceocri- 
nidae, such as the hinge, supplementary or patelloid plates, the anal tube, 
and the peculiarly complicated arm-branching. Several of the Gotland 
species of Calceocrinus are shown to present a very perfect evolutionary 
series. Under the Dicyclica we have first a thorough revision of 
Homocrinus, now first known from Europe. Under Euspirocrinus and 
Cyathocrinus a description of the various modifications of the tegmen and 
of the madreporite is given ; but the author prudently declines to 
advance any homologies. It is suggested that Gissocrinus is not so akin 
to Cyathocrinus as has always been supposed, and it is shown that the 
fusion of the infrabasals in this genus is so irregular that no morpho- 
logical importance can be attached to it, nor can theories of orientation 
be based on it. In dealing with Gissocrinus and Cyathocrinus Mr. Bather 
gives elaborate dissections of the brachials and ambulacrals ; the latter 
were often very complicated, and were provided with articular facets 
and with a nerve-supply from the aboral nervous system. 
There is a note on the colour of fossils, a propos of the differences 
seen to exist between species of Cyathocrinus. Streptocrinus is a little- 
known but a singularly interesting form ; it differs from all known 
* Kongl. Svenska Vet.-Akad. Handl., xxv. (1803) No. 2, 200 pp. and 10 pis. 
