II. 

 General description of the external form. 



(Pysiognomy). 



tSee Tab. I, fig. 1, Tab. II, fig. 1 & 2). 



In its general aspect the present species has on the whole a great resemblance 

 'to the Brisinga endecacnenios Asbj0rnsen as represented in the fauna littoralis Norvegise 

 2"^ volume Tab. IX, fig. 1. From a little circular disc of scarcely more than 1 inch dia- 

 meter, there issue a number of spreading arms or rays (varying from 9 to 12) of an extra- 

 ordinary length (more than 1 foot) and armed along the edges with several rows of long 

 spines. These arms are very sharply defined, and at the base distinctly instricted; after- 

 wards for a short distance rather strongly enlarged, and then again regularly tapering to- 

 wards the point; they stand also so close together at the root that there scarcely appears 

 to be any interval between them. On closer examination there will however be observed 

 (see Tab. 1, fig. 3) in the angle between 2 arms a small peculiar calcareous plate, which 

 belongs to the skeleton of the disc, and which when the arm is removed (see Tab. 1, fig. 6, 

 Tab. Ill, fig. 1) shews 2 semilunar articulating-surfaces separated by an evident interval. 

 On the upper side this interradial plate rises in a tubercular prominence (Tab. 1, fig. 6 d) 

 which is very conspicuous in the upper edge of the disc by its lighter color, and by being 

 for the greater part bare; while the rest of the dorsal surface of the disc is covered with 

 short cylindrical spines growing close together. In one of the corners, at the issue of 2 

 arms, there appears on the dorsal surface of the disc a rough button-shaped prominence 

 (Tab. 1, fig. 3, 4, 6 b) which is the so-called madreporic body. The dorsal side of the arms 

 is very uneven. In their whole length and up to their extreme point (see Tab. I, fig. 12, 

 Tab. II, fig. 1 & 2) there are usually found at regular intervals, numerous well defined half 

 cylindrical transverse band-like ridges, which are sometimes variously sinuous, and generally 

 distinguishable by a more intense color than that of the rest of the arm. These transverse 

 ridges appear on closer inspection to be of a soft fleshy consistency; although they also 

 contain calcareous elements in the form of innumerable closely packed microscopic pedi- 



