STAR-FISHES. 167 



The family Beisingidje includes only two known species, both inhabitants of deep 

 water, where they have an exceedingly wide distribution. The genus approaches 

 Pycnopodia and Crossaster, but in appearance is intermediate between the ophiurids 

 and the star-fishes, since it has a distinctly circumscribed disc like the former, 

 though the long arms are soft as in the latter. JBrisinga endecacnenios has eleven 

 arms, which are nearly smooth, while the nine to thirteen arms of B. coronata have 

 transverse crests of spines. The arms are sometimes a foot long, they are narrow at 

 their insertion into the disc, enlarge considerably towards the middle, where the 

 ovaries are developed, and taper thence to the tip. B. coronata has a single genera- 

 tive organ, with a single opening, on each side of each arm, while B. endecacnenios 

 has a great number of separate small organs, each with its own opening, in a similar 

 position. The water-feet are furnished with sucking-discs. Rows of long spines 

 covered with soft skin border the ambulacral grooves ; this skin is full of small 

 pedicellarise, and groups of pedicellarise are scattered over arms and disc. The 

 creature is extremely fragile, and always breaks to pieces before it can be handled. 



The PteeasteeidjE are furnished with grouj)s of diverging sjiines, on the tips 

 of which a membrane is carried. Uynienaster pellucidus was first dredged in five 

 hundred fathoms off the north of Scotland, and it has since been found that, with 

 perhaps the exception of ArcJiaster, Hymenaster is the most widely distributed genus 

 of deep-water asterids, varying from four hundred to two thousand five hundred 

 fathoms. 



Hymenaster iiohilis is rather a large star-fish, ten inches across. The five anus, 

 each two inches wide, are united to f ach other by a broad web attached to the outer 

 row of the spines which fringe the ambulacral groove, thus transforming the animal 

 into a large jientagon. The entire uiaper surface, the web excepted, is set with 

 bunches of four to six diverging spines about an eighth of an inch long. These spines 

 support, clear of the surface of the disc, a tolerably strong membrane, like the canvas 

 of a tent. Something similar to this occurs in Pteraster. In the centi-e of the back 

 this arrangement is modified to form a brood pouch foi- the young. From five 

 calcareous sujjports, arising from the ambulacral plates below, spring a double series 

 of sjjines, the outer series of three or four diverging in the ordinary way beneath the 

 tent cover, while the inner series of six or eight bend inwards, and have a special 

 membrane stretched between them in such a way that each series forms a fan-like 

 valve, the spines closing when the valve is closed and separating when it is opened. 

 In this central pouch the young are carried. This species was taken in eighteen 

 hundred fathoms, about eleven hundred miles southwest of Cape Otway, Australia. 



Korethraster hispidus was dredged near the Shetland Isles. It is a small star-fish 

 with the whole of its upper surface covered with long spines (paxillse) like sable 

 brushes, masking its true outline. Rows of delicate, spoon-shaped spines border the 

 ambulacral grooves. Another species of this genus, K. pahnatus, has been dredged 

 in the Caribbean Sea. 



Pteraster is the principal genus of this essentially deep-water family. In 7-". 

 inidtipes, of the Norwegian seas, there are four rows of watei--feet, as in Aster ias. 



The AsTROPECTiNii)^ are forms with long rays ending in a point, thus resembling 

 in general shape the Asterida?, from which they differ in having two rows of ambula- 

 cral tentacles, which are usually without sucking discs at their extremity, and' also in 

 the character of the skeleton, which is formed, at least in the dorsal region, of con- 

 tiguous ossicles, often shaped like an hour-glass, and bearing tubercles which are 



