10 Description of Genera and Species. 



it affords the best evidence that the group to which it belongs finds its place in the 

 Lophogastridaj of G. 0. Sars, a family considered by him to be at the head of the great 

 sub- order Schizopoda. Of the four genera described by Sars^ as constituting the family, 

 the forms about to be described are most nearly allied to Gnathophausia, which they 

 closely resemble, though they differ from it in many important particulars. 



Specific Characters. — Integuments nearly smooth or onlj- slightly pitted. Body 

 more elongated than in the other species of the genus and not so much flattened. The 

 median longitudinal keel does not reach the posterior margin of the carapace, and none 

 of the keels are denticulated or crenulated. The tail is almost free from longitudinal 

 keels. 



General Description. — The general length of the body from the tip of the rostrum 

 to the end of the telson is, on an average, about 30-32 mm. The form is elongated and 

 moderately slender, but not so much so as in Gnatliophausia, the females being slightlj' 

 more robust than the males. The body is somewhat applanated, which causes it to be 

 fossilised so as to be generally seen back upward. The integuments are strong and 

 chitinous, though thin and ornamented in their thicker parts with a minute pitting and 

 slight wrinkling, and also with broad marginal bands and pronounced longitudinal 

 keels. In most of the specimens the chitinous nature of the test is disguised by its 

 being calcified or phosphatised and sometimes filled in with galena. The calcification 

 may have begun during life. The other processes seem to have taken place during 

 decay and fossilisation. In some specimens green nodular grains are found which 

 suggest the presence of glauconite. This filling in of the test is not altogether a 

 disadvantage, as it has helped to keep some of the organs from being flattened out, and 

 when it is partial, as it sometimes is, it allows of some of the organs being seen through 

 parts of the test which have not been thus affected, so that one is often able to study 

 the sternal arrangements, through the almost transparent carapace, which otherwise 

 would be hidden by it. 



The trunk, which makes up half the length of the body, if we consider the eyes to 

 be dorsal structures and not modified limbs, is built Tip of thirteen segments each 

 bearing a pair of bi-ramose limbs. The first six are more or less confluent and are in 

 more or less vital attachment with the carapace, their limbs being spe(^ially modified to 

 perform tlie function of sensory and mouth organs. The remaining seven trunk 

 segments, although more or less fused together, are well marked off from each other by 

 strong infolds of the test on the sternal parts, thus forming a ver}- rudimentary 

 endophragmal system, while the dorsal part of each segment is quite covered in. but 



G. O. Sars. " Report on the Schizopoda," Results of Voyage of H.M.S. Challenger, 1873-76. 



