350 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



The more or less elongate body of a holothurian terminates anteriorly in a 

 circle of tentacles surrounding the mouth, but these are very sensitive and highly 

 contractile organs and when the animal is alarmed or irritated, they are withdrawn 

 (or folded) into the anterior end of the body-cavity and the body appears to 

 terminate in a blunt point. Preserved holothurians are usually in this condition 

 unless some artificial means are used to prevent the contraction. The tentacles 

 differ in form in different groups, but among Peruvian holothurians they are either 

 arborescent, i. e. irregularly branched from near the base, or peltate, i. e. the 

 branches are confined to the tip, where they form a more or less flat and circular 

 disk. The body of a holothurian is more or less soft and smooth, but carries, 

 either scattered all over the surface, or confined to five longitudinal areas (the 

 ambulacra), little outgrowths or projections which like the tentacles are highly 

 contractile. When these end in a flat sucking disc, they are called pedicels or 

 tube-feet, but when more or less pointed, they are papillae. Papillae are often 

 borne on large conical elevations called warts. The positive identification of 

 holothurians is only possible when the internal anatomy and the calcareous 

 particles in the skin (usually microscopic) are carefully examined. 



Key to the Sea-Cucumbers of the Peruvian Coast. 



Tentacles peltate. 

 Body with large warts and conical papillae on the back and sides 



Stichopus fuscus 



Body without warts but covered by numerous pedicels . . Holothuria c.hilensis 

 Tentacles arborescent. 



Tentacles 20, or sometimes fewer, either equal or more or less unequal 



in size Phyllophorus peruvicinm 



Tentacles 10. 



Pedicels arranged in more or less distinct series confined to the ambu- 

 lacra, at least on the ventral surface. 

 Pedicels in distinct series along the dorsal ambulacra; body 



elongated as usual in holothurians. 



Pedicels relatively few in two series along each ambu- 

 lacrum Cucumaria leonina 



Pedicels more numerous, in, three or four series along each 



ambulacrum Cucumaria godeffroyi 



Pedicels wanting on back, but papillae present ; body with ends 



upturned and thus ascidian-shaped Colochirus peruanus 



Pedicels numerous, irregularly scattered all over body .... Thyone gibber 



Stichopus fuscus. 

 H. Ludwig, 1874. Arb. Zool.-Zoot. Inst. Wurzburg, 2, p. 21. 



This species has been recorded from San Diego, California ; Mazatlan, Mexico ; 

 Machalilla, Ecuador, and the west coast of Patagonia (see Ludwig, 1898a) and 

 therefore doubtless occurs in the Chile-Peruvian region. It reaches a length of 



