diff --git a/src/sourmash/index.py b/src/sourmash/index.py
index 5b57860661..0966f0ebb7 100644
--- a/src/sourmash/index.py
+++ b/src/sourmash/index.py
@@ -993,9 +993,18 @@ def select(self, **kwargs):
 class DirectoryIndex(Index):
     """
     Notes:
+    * manifests for directories are _generated_ by MultiIndex :grin: :shrug:
     * Lazy - loads signatures only when requested
+    * could/should be implemented on top of FSStorage?
+    * maybe this becomes StorageIndex? basically a storage with a manifest?
+    * different from MultiIndex because it uses pre-existing manifest and
+      lazy loading/does not keep signatures in memory.
+    * different from LazyLoadedIndex because that requires a concrete index.
+    * different from LazyMultiIndex because that also requires a concrete
+      index.
     """
     def __init__(self, parent, manifest):
+        "Constructor; 'parent' is the top-level directory."
         self.parent = parent
         self.manifest = manifest
 
@@ -1019,12 +1028,18 @@ def signatures(self):
             yield ss
 
     def signatures_with_location(self):
+        "Load and return all of the signatures in the manifest."
         for location in self.manifest.locations():
             fullpath = os.path.join(self.parent, location)
             for ss in load_signatures(fullpath):
                 if ss in self.manifest:
                     yield ss, fullpath
 
+    def select(self, **kwargs):
+        "Run 'select' on the manifest."
+        new_manifest = self.manifest.select_to_manifest(**kwargs)
+        return DirectoryIndex(self.parent, new_manifest)
+
     def __len__(self):
         return len(self.manifest)
 
@@ -1034,11 +1049,6 @@ def insert(self, *args):
     def save(self, *args):
         raise NotImplementedError
 
-    def select(self, **kwargs):
-        "Run 'select' on the manifest."
-        new_manifest = self.manifest.select_to_manifest(**kwargs)
-        return DirectoryIndex(self.parent, new_manifest)
-
 
 class LazyLoadedIndex(Index):
     """Given an index location and a manifest, do select only on the manifest
diff --git a/src/sourmash/sourmash_args.py b/src/sourmash/sourmash_args.py
index 64c118fb4b..a8c0823a7c 100644
--- a/src/sourmash/sourmash_args.py
+++ b/src/sourmash/sourmash_args.py
@@ -18,7 +18,8 @@
 
 from .logging import notify, error, debug_literal
 
-from .index import (LinearIndex, ZipFileLinearIndex, MultiIndex)
+from .index import (LinearIndex, ZipFileLinearIndex,
+                    MultiIndex, DirectoryIndex)
 from . import signature as sigmod
 from .picklist import SignaturePicklist, PickStyle
 from .manifest import CollectionManifest
@@ -270,6 +271,13 @@ def _multiindex_load_from_pathlist(filename, **kwargs):
     return db
 
 
+def _directoryindex_load(filename, **kwargs):
+    "Load collection from a directory with a manifest."
+    db = DirectoryIndex.load(filename)
+
+    return db
+
+
 def _multiindex_load_from_path(filename, **kwargs):
     "Load collection from a directory."
     traverse_yield_all = kwargs['traverse_yield_all']
@@ -309,6 +317,7 @@ def _load_zipfile(filename, **kwargs):
 # all loader functions, in order.
 _loader_functions = [
     ("load from stdin", _load_stdin),
+    ("load from directory w.manifest", _directoryindex_load),
     ("load from path (file or directory)", _multiindex_load_from_path),
     ("load from file list", _multiindex_load_from_pathlist),
     ("load SBT", _load_sbt),