367 



em Africa. Sent to the Cabinet of the Society by Dr. G. A. 

 Perkins. The color of the body and spines is uniformly bluish 

 black above ; a little lighter below. 



Observations. Having opened one specimen preserved in 

 alcohol, the following peculiarities were noticed. The lantern 

 (of Aristotle) nearly reaches the superior roof of the disc. 

 The auricles form an arch over the zones of pores thus corres- 

 ponding to the ambulacral spaces. The pyramids of the lantern 

 alternate between the auricles and correspond to the interam- 

 bulacral spaces. Each auricle sends two powerful muscles to 

 the point of the pyramids but in such a manner, that one pyramid 

 receives its two muscles from two auricles. The other muscles, 

 moving the pyramids, and pieces of the lantern are attached to 

 the auricular and interambulacral ridge. The intestine is wound 

 once around the lantern, and reaches the anus at the same place 

 where the oesophagus passes over the lantern. Its course is 

 undulated, descending and ascending. From the top of the 

 lantern it descends between two auricles, and forms a winding 

 on the interambulacral space, where it ascends and passes inside 

 the auricle over its muscles and descends again on*the opposite 

 side, and so on for the five principal segments of the body. The 

 intestine is suspended at the inner wall by means of delicate 

 ligaments. The ovaries rest on the interambulacral windings of 

 the intestine, and are contiguous near the summit. There is 

 left a free and well defined space, corresponding to the ambul- 

 acra, for the circulation of the water which enters through the 

 pores. The fluid passes under the arch of the auricles, soaks 

 the masticating apparatus whence the current may empty through 

 the mouth. The water might also enter the mouth, and passing 

 under the auricular arch, fill up the whole cavity of the animal. 



5. EcHiNOCYAMus MINIMUS Girard. The smallest species 

 hitherto known of this genus, the largest specimen I have seen 

 being only a sixth of an inch in longitudinal diameter. Its gen- 

 eral form is that of an ellipse posteriorly attenuated. The upper 

 surface is depressed, nearly plane ; the inferior surface is slightly 

 concave. The mouth is proportionally large ; the anus is nearer 

 the posterior margin than to the mouth. 



Found within a Spatangus meridionalis from the Mediter- 

 ranean. This species is alluded to in Prof. Agassiz's " Mono- 



