1870.] 61 [Morse. 



Myriapods with other insects, while its antennae are bifid, a crusta- 

 cean character. 



Speculating on the probable ancestry of insects (including the 

 Arachnids and Myriapods) he would trace their descent from a form 

 resembling in some respects the hexapodous larva of Pauropus, which 

 seems reproduced in larval Myriapods (Julus) ; in larval Arachnides 

 (mites) ; and larval and degraded forms of many insects (such as the 

 flea, louse, bat-tick, Braula, Chionea, female Anisopteryx, (Eceti- 

 cus, the Thysanura, etc., etc.,) all showing a strong tendency to 

 assume a hexapodous Podura-like form, which may be compared with 

 the Nauplius form through which Fritz Miiller, Dr. Dohrn, and 

 Haeckel consider all crustaceans to pass. For this ancestral form he 

 had proposed the term Leptus, from the fact that like Nauplius, 

 which was first supposed to' be an adult Entomostracan, the larval 

 form of Trombidium had been described as a genus of mites under 

 the name of Leptus, and was supposed to be an adult. The Leptus 

 was hexapodous, and bore a general resemblance to the Poduras, and 

 the young of Pauropus, though the body (especially the abdominal 

 portion) was not segmented. He thought there were several parallel 

 lines of descent, diverging from some forms such as the Tardigrades 

 or Linguatulse, or both, and probably others, which again might- 

 have descended from some terrestrial worm like Peripatus, and other 

 generalized types of worms. 



Prof. Edward S. Morse made a few remarks on the struc- 

 ture of the common sipunculoid worm of the coast, JPhas- 

 colosoma. 



It occurs in the greatest abundance at Eastport, Me., living in the 

 shells of Dentalium principally, though found in other species. The 

 worm takes possession of the empty shell, and partially plugging it 

 with hardened mud, forms a constricted aperture. Owing to the 

 translucence of the animal, the internal organization can be studied 

 to advantage. He referred to certain features in its structure, and 

 in the character of its earlier stages, as throwing additional light on 

 the affinities of the Brachiopods with the Vermes. 



Dr. Samuel Kneeland gave an account of a visit made by 

 him during the past summer, to the country lying about the 

 upper Mississippi. He described the beauty and attractive- 



