170 THE PROCEEDINGS OF THE LINNEAN SOCIETY 



milled ring prominent, grooves large. Maj. diam, 140 ; min., 

 115 ; alt., 63 ; actinosome 25, bat very irregular in shape. 

 Largest spines scarcely 10 mil. in length. 



Sub-Family Laganidje, Desor, 1857. 



Outline pentagonal, petals crenulate, connection between floors 

 by walls running parallel to the edge of test. I. extremity 

 narrow on actinal side, ambulacral furrows straight. 



Genus I. — Laganum, Klein, 1734. 



Test generally large, sub-pentagonal, depressed, with swollen 

 edge. Petals short, closed. Pores congregated. Actinal surface 

 flat, with peristomal star, and porous ambulacra not reaching the 

 margin. Primary tubercles few, and uniformly scattered, mill- 

 iaries more numerous, anus inframarginal. 



Laganum bonami, Klein. 



A small sub-pentagonal species, with somewhat long petals, 

 which are not quite closed. Anus and mouth not far apart, the 

 latter large and pentagonal. Length, 33 ; breadth, 28 millim. 

 Rather common in Port Jackson and in Tasmania. 



Laganum depressum. Lesson. 



More flattened and larger than the last; edge thinner, not 

 swollen, anus nearer edge, and transversely elliptical or circular ; 

 apical system larger. Peristomal star distinct, while on the last 

 species it cannot be traced. The pairs of pores become more 

 separated as they near the tip of petals, but never so indistinctly 

 conjugated as in L. Bonami. Length, from 27 to 79 ; breadth, 

 from 23 to 70 mil. It is found in the Pacific and Indian Oceans 

 as well as Australia. 



Genus, Peronella, Gray, 1855. 



Regarded as a subgenus only by Agassiz. The Genital pore 

 far away from the abactinal system in the I. Partitions ramify, 

 extending half-way to the centre instead of forming a narrow 

 belt of three or four near the edge. Four G. openings. 



