359 
Psolidiella n. g. 
Body Psolus-Vike, with a distinet ventral sole, which is, how- 
ever, not limited from the rest of the body through a sharp edge. 
Outside the sole the body all over provided with tubefeet which 
do not show any serial arrangement. Calcareous deposits not in 
the shape of distinet, overlapping scales. The posterior part of the 
intestine, with its mesentery, in the left ventral interradius. 
Genotype: Psolidiella nigra n. sp. 
Though superficially resembling a Psolid this form does not 
really belong to the Pso/ws-group, as is shown beyond any doubt 
through the faet that the posterior part of the intestine is in the 
left ventral interradius. As has been pointed out by Hj. Øster- 
gren the situation of the posterier part of the intestine appears to 
be of primary importance for the subdivision of Dendrochirotes, 
the Cucumariids and the Phyllophorids having it in the left, the 
Psolids having it in the right ventral interradius. 
The species here made the type of the new genus Psolidiella 
I was at first inelined to refer to the genus Psolidium^ until the 
discovery of the situation of the hind part of its intestine in the 
left ventral interradius revealed the faet that it is a Cucumariid, 
not a Psolid. The species hitherto referred to Psolidium show very 
great diversity in shape; some of them resemble true Psolus in 
shape and scaling, others are more Cucumaria-WkQ in shape and 
devoid of a true scale-covering; the suggestion therefore lies at 
hånd that all these various forms do not really belong to one and 
the same genus. The type of the genus Psolidium, Ps. dorsipes 
Ludwig, (— I have been able to examine a specimen^) belonging to 
the Paris Museum, and beg herewith to offer my best thanks to 
Professor L. Joubin for his kindness in lending me the specimen 
for examination —) agrees with true Psolids in regard to the situa¬ 
tion of the intestine. It is to be expected that the other species 
The specimen unfortunately had been opened just in the critical point, 
the posterior end of the right ventral interradius, and part of the intest¬ 
ine removed. Enough, however, remained to show beyond doubt that the 
posterior part of the intestine really lies in the right ventral interradius, 
not in the left. 
