SQUILLOIDEA. 533 



small, the posterior smallest. Hand broad and finger as long as hand. 

 Last three pairs of thoracic feet rudimentary, consisting of a basal joint 

 and a bifid extremity, which is naked and hardly appears to be arti- 

 culate. The segments of the body to which these organs severally 

 pertain were all distinct, excepting those belonging to the mouth organs 

 and first pair of feet, which appeared to be united in one. The last 

 four segments of the thorax are very slender, the diameter being less 

 than one-third the length. 



Abdominal segments all narrow oblong, gradually enlarging poste- 

 riorly ; a spine from posterior part of each, laterally. Last abdominal 

 segment lamellar, distinctly composed of two segments, a suture near 

 its base marking the junction of the two. This segment is broadest 

 at middle and anteriorly; the two lateral teeth are just below the 

 middle, the other four teeth are all on the posterior margin, and are 

 quite near together, and the margin intervening is minutely denti- 

 culate. The abdominal feet consist of two oblong lamellse on a com- 

 mon base, each plate jointed, one near base, the other below middle, 

 and both are ciliate. No branchial appendages were observed. 



This species is near the liyalina. But according to Leach's figure 

 (Voy. of Capt. Tuckey to the River Zaire), the hyalina has the abdo- 

 minal segments hardly oblong, while in our species they are more 

 than twice as long as broad, and the medial posterior spine of the cara- 

 pax is marginal, and this margin is bent upward, which is not the fact 

 with the angusta. The proportions vary correspondingly in other 

 respects. The base of the superior antennae, moreover, is sparingly 

 longer than the beak in the hyalina. 



It differs from the gracilis in having the medio-dorsal spine just 

 back of the posterior margin instead of on the margin, in its more 

 slender filiform arms, its spinule on the spinous prolongation of the 

 posterior angles of the carapax (see Edwards's figure, in Cuv. Regne 

 An., pi. 57, f. 3). 



APPENDIX TO SQUILLOIDEA. 



WE append here a description of a few young individuals, which 

 probably belong in this group, among the Schizopoda. 



159 



