82 PROCEEDINGS OF THE ACADEMY OF [1886. 



plates, which are connected by suture, except at their inner 

 ends, where they leave generally a slit-shaped opening. The 

 muscle-plates extend over the greater part of the ventral surface, 

 and constitute a more or less elevated pyramid, with an open 

 space in the centre. The central space is closed by cornpara- 

 tivel}' small interradials and the summit plates ; the latter, as a 

 rule, are more extensively developed than in the Haplocrinidse. 

 The arms are extremely long, closely folded together. They are 

 composed of quadrangular joints, suturally connected, and 

 moved upon the radials by means of strong muscles. The anal 

 opening, where it has been observed, is intermediate between two 

 muscle-plates. Column round, with a small central canal. 



(7. CuPRESsocRiNiD^. Calyx large. Base dicyclic. Theunder- 

 basals are anchylosed, and form a solid disk, which is succeeded 

 by five basals. The radials are provided with large muscle-plates, 

 which are laterally anchylosed, and form a continuous plate cov- 

 ering a large portion of the bod}^ It stands on a level with the 

 upper faces of the- radials, and is pierced by the anus and the 

 ambulacral openings. The arms are simple, closely folded to- 

 gether, and composed of massive, wide, quadrangular pieces, 

 which, being connected by suture, moved in a body upon the 

 radials. Column strong, containing a large central canal sur- 

 rounded by peripheral ones. 



D. Gasterocomid.e. Base dicyclic ; basals and underbasals as 

 in the Cupressocrinidte. Radials large; their articular facet 

 lateral, horseshoe-shaped, covering almost the whole outer face of 

 the plates. They are provided with large axial openings, which 

 occupy the median portions of the facets, and are notched at their 

 upper end to pass in the ambulacral canal. The anal opening is 

 dorsal, placed between two radials, and either succeeds the anal 

 plate, or this succeeds the opening. The interradial plates are 

 small occupying the equatorial zone. The oral plate is very 

 large, excentric, and surrounded by four large proximals, its pos- 

 terior side resting against the radials. Arms recumbent or widely 

 divergent. 



Family XIII. HAPLOCRINIDtE. 



Under this family we place only the two genera Haplocrinus 

 and Allagecrinus. Roemer referred to it Haplocrinus and Gocco- 

 crinus, in which he was followed by Zittel and S. A. Miller. 

 Schultze, like us, referred Goccocrinus to the Platycrinidse, but 



