62 



or strengthened such natural divisions as Dicotyledonous and 

 Monocotyledonous plants, over all natural groups ? Is it the stand- 

 ard of every type or group ? Is it the proof of its foundation in 

 nature, that its members exhibit materially their unity by iden- 

 tity of organization at any time of their embryonic development? 

 "We think that it is impossible to answer this question for want 

 of embryological data, but in relation to the Tajnioids, which we 

 will call a family, its truth is remarkably evident. We form 

 a natural group of all those Tcenias, the embryos of which show 

 that disk-like body with six spines. We might call them Hexe- 

 chinidaj. Many genera with very different structure in relation 

 to the reproductive organs, the number and disposition of the 

 hooks, the form of the proboscis, &c. &c., are included in it. 

 Even their forms when adult are not the same, but we have a 

 doubt whether we ought not, in basing, as Agassiz has taught us, 

 families upon foi'ms, to make, at least in the lower animals, this 

 allowance, that the guiding form is often not exhibited in the 

 adult animal, but only in a much earlier, perhaps in its embryonic 

 state. We allude here particularly to all those animals in which 

 an alternation of generation is observed, such as Cirripeds, etc. 



The neiv genus, which we found upon the structural peculiari- 

 ties mentioned above, we will call Liga, and the species, from its 

 many yellowish-brown dots, punctata. 



A full description of both genus and species, with drawings, 

 will be given on some future occasion. 



Dr. Gould asked if there is around the mouth of the common 

 tapeworm {^T<snia soliuin) a row of hooks, as is commonly fig- 

 ured in descriptions of the head of this animal. 



Dr. Weinland replied that there is a row of hooks at the base 

 of the proboscis, which move with the invagination of this organ, 

 and which consequently may appear in different jDositions. 



Dr. Gould asked where the embryos of the tapeworm were 

 obtained. 



Dr. Weinland replied that they exist in the articulations of the 

 old worm, in all stages of development, and may be removed by 

 incision and pressure upon the joint. 



Prof. Agassiz observed that the ova of Botriocephalus latus, 

 which is common in Switzerland, may possibly be introduced into 

 the human body by the vegetables used for salad, which are ma- 



