HOLOTHURIOIDE A 42 1 



Family Molpadiid.^ 



Diagnosis the same as that of the order. 



No Molpadid is known from the British seas, but it is very 

 probable that the genera Trochostoma Danielssen and Koren and 

 Ankyroderma Danielssen and Koren will be represented there, 

 or the genus Molpadia Cuvier, if these two genera cannot be 

 kept separate from the latter, as is the opinion of H. L. Clark in 

 his recent monograph of this order. Without taking a definite 

 position towards the question, the author is here following H. L. 

 Clark in regarding Trochostoma and Ankyroderma as synonyms of 

 Molpadia. 



1. Molpadia Cuvier. (Fig. 256.) 



Tentacles 15, with 1-3 pairs of digits and a larger terminal 

 digit. Body stout, with a distinct but short " tail ". Radial 

 pieces of calcareous ring with conspicuous bifurcate posterior 



Fig. 256. — Molpadia arctica. Slightly reduced. (After Danielssen and 

 Koren, Norwegian North Atlantic Exp. Holoth.) 



prolongations. Calcareous deposits tables, often in very imper- 

 fect state, perforate plates or more or less fusiform rods. Anchors 

 usually present, though often very scarce, attached to racquet- 

 shaped plates, usually arranged so as to form a rosette (Fig. 

 257, 1). Phosphatic deposits often present. Anal teeth usually 

 present. 



Seven species of this genus are known from the N.E. Atlantic 

 and the Arctic European seas, namely Molpadia albicans 

 Theeli (Syn. Trochostoma albicans Theel), found at 16° 38' N., 

 20° 44' W., 3200 m. ('' Talisman "), elsewhere known from the 

 east coast of N. America and the Indo-Pacific, 486-3200 m. ; 

 M. arctica (v. Marenzeller) (Syn. Haplodactyla arctica v. Marenz.), 

 from East Greenland to Finmark and the Kara Sea, ca. 200-400 m. ; 

 M. blakei (Theel) (Syn. Trochostoma blakei Theel ; Tr. blakei, var. 



^ H. L. Clark refers this species to the genus Caudina 



