SUB-CLASS EPECTINATA Distinguished from the Pectinifera by the absence of pectines and of a long tail-like termination to the body, by the presence of not more than i i somites in the abdomen, excluding the pregenital somite, and of at most four pairs of small appendages upon the abdomen in the embryo. Also when lung-sacs are retained, they belong to the first and second abdominal somites not to the third, fourth, fifth and sixth.