Here are the identified issues in the provided dataset files:

1. **Issue**: Missing License Information in README
   - **Evidence**: 
     ```markdown
     ## Dataset Description
     - **Homepage:** [Github](https://github.com/spyysalo/bc2gm-corpus)
     - **Repository:** [Github Repository](https://github.com/spyysalo/bc2gm-corpus)
     - **Dataset Creator:** [BioCreative II Gene Mention Task](https://biocreative.bioinformatics.udel.edu/tasks/biocreative-ii/)
     - **License:** 
     ```
   - **Description**: The README.md file does not provide information about the license under which the dataset is distributed. This is important for users to understand the usage rights and restrictions of the dataset.

2. **Issue**: Inconsistent Naming of Validation Split
   - **Evidence**: In `dataset_infos.json`:
     ```json
     "splits": {
         "train": {"name": "train", "num_bytes": 6095172, "num_examples": 12501, "dataset_name": "bc2gm_corpus"},
         "validation": {"name": "validation", "num_bytes": 1215951, "num_examples": 2501, "dataset_name": "bc2gm_corpus"},
         "test": {"name": "test", "num_bytes": 2454621, "num_examples": 5001, "dataset_name": "bc2gm_corpus"}
     }
     ```
     In `bc2gm_corpus.py`:
     ```python
     return [
         datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"filepath": downloaded_files["train"]}),
         datasets.SplitGenerator(name=datasets.Split.VALIDATION, gen_kwargs={"filepath": downloaded_files["dev"]}),
         datasets.SplitGenerator(name=datasets.Split.TEST, gen_kwargs={"filepath": downloaded_files["test"]}),
     ]
     ```
   - **Description**: The `dataset_infos.json` file refers to the validation split as "validation" while the `bc2gm_corpus.py` file refers to it as "dev". This inconsistency can lead to confusion and potential errors in data handling.

3. **Issue**: Missing Information in Dataset Features Description
   - **Evidence**: 
     ```json
     "features": {
         "id": {"dtype": "string", "id": null, "_type": "Value"},
         "tokens": {"feature": {"dtype": "string", "id": null, "_type": "Value"}, "length": -1, "id": null, "_type": "Sequence"},
         "ner_tags": {"feature": {"num_classes": 3, "names": ["O", "B-GENE", "I-GENE"], "names_file": null, "id": null, "_type": "ClassLabel"}, "length": -1, "id": null, "_type": "Sequence"}
     }
     ```
   - **Description**: The dataset features description in `dataset_infos.json` does not include the lengths for `tokens` and `ner_tags`. This can affect the understanding of the dataset structure and hinder data processing tasks.

These issues should be addressed to ensure the dataset is well-documented, consistent, and usable by the research community.