192 Echinodermata. 



and intestine. There are four pairs of arms of which the anterolateral and 

 posterior pairs are the longest and have reticular spicules. The anterior and 

 antero-internal arms are shorter, with simple spicules. There are no ciliated 

 epaulettes, but the lobes of the ciliated band are greatly developed. There are 

 three in the angle of the posterior arms, the median one being the larger, one 

 lateral and two dorso-lateral pairs. 



Niemiec (*) describes the minute structure of the tube-feet in Asteriscus verru- 

 culatus, Psammechinus miliaris, Sphaerechinus brevirostris, and Brissopsis lyrifera, 

 and compares his results with those of his predecessors. He discusses the mecha- 

 nism of the suckers of Asteriscus, and finds them to contain vertical muscular 

 fibres which tend to produce a vacuum by their contraction, together with horizontal 

 ones which compress the acetabular cavity and act in opposition to the longitudinal 

 muscles. The calcareous elements in the suckers of the Urchins help to oppose 

 the external pressure. They do not afford any means of distinguishing the re- 

 gular Urchins from the Spatangoids. The duplex terminal disc is simple and not 

 tetrapartite. On the other hand, Perrier ( 7 ) reasserts the presence of eight pieces 

 in the terminal disc of the regular urchins and defends his dews about its value 

 for systematic purposes. Niemiec ( 2 ) admits the doubly tetrapartite character of 

 the disc, but regards it as homologous with the spicules of other Urchins in which 

 it is missing, and finds abundant transitional forms. 



VI. Holothuroidea. 



See also Howell. supra, p 184. 



Lampert (S 2 ) notes the great tendency to variation exhibited by certain or- 

 gans of the Holothurians. Species which have the feet scattered in the adult, may 

 present a linear arrangement when young, as in Thyone and Thyonidium, while in 

 Stic/iopus the reverse is the case. Large examples of H. Graeffei also have a linear 

 arrangement of the feet. The characters of the tentacles are fairly constant, but 

 those of the Cuvierian tubes vary greatly, while the limestone deposits are ex- 

 tremely regular, only a few cases of alteration with age being known. 



Lampert ( 2 ) gives a general account of the anatomy of the Holothurians [nothing 

 new] , together with a more detailed description of the various forms of calcareous 

 armature, according to its appearance in the various families. They fall into se- 

 veral groups, but can be reduced to two fundamental forms, the Stiihlchen and 

 Bindekorper of Semper, the latter lying deeper than the former. The descrip- 

 tions of these must be consulted in the original. 



Pocta describes small limestone plates from the Chalk of Bohemia which he re- 

 fers to the genus Psolus. 



Rauff gives an analysis of Loven's memoir on Pourtalesia. [See Bericht for 

 1884 Ip 174.] 



Petit f 1 ) beschreibt die gewohnlich als Tastpapillen aufgefaCten Bildungen bei 

 Xynapta als Hautdrusen und constatirt. daB die Thiere Wasser aus der Leibeshohle 

 durch den After nach aufien befordern konnen, ohne daB sich am Darrne Off- 

 nungen finden lassen. Die iibrigen anatomischen Notizen enthalten nurBekanntes. 



[P. Mayer]. 



