204 



PSOUD.E. 



of the Ascidian Mollusca. When the tentacula of the 

 Psolus pliantapus are withdrawn, the animal has all the 

 aspect of an Ascidia ; so striking, indeed, is the resem- 

 blance, that twice have naturalists of repute been deceived, 

 and twice has it been figured as an Ascidia. 



The body of this animal measures from six to eight 

 inches in length, and from two to three in height. It is of 

 an oblong form, and turned up at both extremities. Be- 

 neath, there is a soft oblong square disk, the surface of 

 which is studded with three longitudinal rows of suckers, 

 which are large and strong. There are from two to three 

 placed across the breadth of each row, but at each extre- 

 mity of the disk the suckers increase in number, so that 

 the ends of the rows are sometimes connected by transverse 

 rows of suckers. The spaces between them are smooth. 

 All the rest of the body is covered with a tough coriaceous 

 skin of a deep brown colour ; beneath it is lighter, and there 

 are sometimes orange dots. This skin is strengthened by 

 a scale-like arrangement of short spines placed on tuber- 

 cles, so that the integument of the Psolus approaches in its 

 character to that of the true Starfishes. Along the back 

 are two deep longitudinal furrows, which indicate the two 

 rows of suckers wanting, or rather obsolete. The hinder 

 part is somewhat conical, and more turned up at the vent 

 than the anterior, which is rather obtuse and bears the 

 large head. This head or neck is about an inch in length, 

 and covered with a soft skin, of a more or less reddish 

 colour, with orange or scarlet spots, and a few conical 

 white papillae, which Dr. Johnston states are arranged 

 in five imperfect rows. At its extremity are five large 

 triangular, shelly, pedunculated tentacula of a bright 

 orange colour, with darker spots. These tentacula are 



