t 
SIGNIFICANCE OF LARVAL MANTLE OF FRESH-WATER 
MUSSELS DURING PARASITISM, WITH NOTES ON A 
NEW MANTLE CONDITION EXHIBITED BY LAMPSILIS 
LUTEOLA. 
By CHESTER N. BLYSTAD, 
Scientific Assistant at Large, U. S. Bureau of Fisheries. 
Contribution from the U. S. Fisheries Biological Station, Fairport, Iowa. 
J- 
CONTENTS. 
Page 
Introduction 203 
Mantle cells of glochidium 204 
Parasitism of species of Anodonta 205 
Ingestion of food 206 
Formation of ‘ ‘ mushroom body ” 208 
Completion of definitive mantle 210 
Metamorphosis of Lampsilis luteola 211 
First encystment stage of Lampsilis luteola 212 
Absence of ‘ ‘ mushroom body ” 213 
Formation of definitive mantle , 213 
Middle parasitic stage 214 
Final period of parasitism 214 
Occurrence of a placental-like relationship between Lampsilis luteola and host 217 
Specialization as indicated by mantle cell conditions 218 
Literature cited 218 
INTRODUCTION. 
The developmental stages of fresh-water mussels while parasitic on fishes 
have received considerable attention from German workers, different species of 
Anodonta having been used as subjects for classical studies. These mussels have no 
commercial value, and there has been no artificial propagation in Germany that 
might have led to studies of other unrelated forms. In this country, however, we 
have the artificial propagation by the U. S. Bureau of Fisheries 1 of several species 
of mussels, particularly of Lampsilis luteola, which is of a different genus from those 
studied abroad and one in which, therefore, the developmental stages might be 
dissimilar to those described for Anodontas. In this connection the examination 
of larval mussels of this species has revealed a condition of the larval mantle cells 
considerably different from that reported by German writers. 
1 The artificial propagation here mentioned has been carried on under the direction of the Fairport Biological Laboratory. 
The author is particularly indebted to H. W. Clark, scientific assistant, of the Fairport staff, for criticism in reviewing the 
manuscript and for suggestions during the course of the work. 
203 
