10 Echinoderma. 



arms is of two kinds : 1. snmolh and longitudinally striated fibres of epithelial 

 origin, like those of other Echinoderms. These are grouped together in rings, 

 each fibre bearing many nuclei on its inner side ; and they form the most ventral 

 of the paired muscular bundles; 2. the other three bundles between the arm- 

 joints and those of the cirri consist of contractile spindle cells, which spread out 

 brush-like at their ends, and are almost indistinguishable from elastic fibres. - 

 The dorsal nervous system of Crinoids is probably of ectodermic origin, like the 

 dorsal nerves of Asterids, but it has assumed a secondary position in the meso- 

 blast. The ventral system is probably derived from the ambulacral one , which 

 has no central organ. 



Korschelt ( 2 ) figures several ova of Antedon rosacea, some with amoeboid nuclei, 

 and others with striations in the protoplasm immediately round the nucleus. 



Carpenter describes an abnormal disk of Actinometra notata (sp. n.). The 

 groove-trunk which would naturally supply the hinder arms of the right side 

 terminates abruptly before reaching them ; and their ambulacra are connected 

 across the anal interradius with the single groove-trunk which comes round the 

 other side of the disk to supply the hinder arms of the left posterior ray. 



The publication of Loriol's f 1 ) descriptive work on the French Jurassic 

 Crinoids is now concluded. It contains a mass of information respecting structural 

 details from which the following points may be noted. - - The asymmetry of the 

 radials in Eudesicrinus. They show a distinction of bivium and trivium and rest 

 below on a simple support : the absence of true articular surfaces on the radials 

 and first two brachials of Guettardicrinus, all these plates being united by simple 

 synostosis : - - the occurrence of infrabasals in two species of Millericrinus : - 

 the preservation of an ambulacral skeleton on the pinnules of Millericrinus regu- 

 laris and Pentacrinus angulatus : - - the occurrence of abnormal hexamerous stems 

 in P.jurcnsis, and of tetramerous stems in 3 species of P. and also in Balano- 

 crinus pentagonalis : - - the apparent absence of a second radial in two species of 

 Antedon, so that the axillary is articulated directly to the primary radial : the 

 presence of two pinnule facets on the arm joints of Gymnocrinus Moeschi. 



Loriol ! 2 ) describes a singular new genus of the Pentacrinidae, Austinocrinus , 

 from the Cretaceous of Turkestan. The petals of the articular rosette in the centre 

 of each stem-joint are quite short, and the periphery of the surface is marked by 

 radiating striae. 



Bather (') describes a remarkable new genus of Eugeniacrinidae which he calls 

 Trigonocrinus. The calyx is tetramerous, though triangular in section. It has a 

 b:\sal ring of four pieces, but one is so atrophied as to be almost invisible, and 

 the two radials above it are only half the size of their fellows, each of which has 

 two lateral spine-like processes, while the adjacent processes of the smaller radials 

 are aborted. The angles of the calyx are thus produced upwards into spines 

 homologous with the petals of Phyllocrinus , but the articular facets between them 

 are reduced to a minimum'being represented by a mere rim around the ventral 

 opening of the calycal cavity. The latter is sunk down into the radials and had 

 a wide opening below, which was probably filled by the upper part of the top 

 stem joint. This form appears to have been evolved from a primitive iso-penta- 

 merous type, such as Eugeniacrinus caryop/tyllatus, by atrophy and fusion following 

 a sport, which effected the loss of one basal and one radial. One side of the calyx 

 then increased at the expense of the other, the two atrophied radials eventually 

 fusing and the basal below them almost disappearing. - - Having examined Zittel's 

 preparations of the axial canals within the calyx of Eugeniacrinus. Bather ( 2 ) con- 

 firms that author's account of their distribution, and gives some additional details. 

 The axial canal of the stem passes up into the radial circlet and gradually widens. 



